GIA's Colored Stone Essential's Reference Guide

ESSENTIALReference Guide

C o l o r e d S t o n e

ESSENTIALReference Guide

C o l o r e d S t o n e

©© 1999 The Gemological Institute of AmericaAll rights reserved: Protected under the Berne Convention.No part of this work may be copied, reproduced, transferred, or transmitted in any form or by any means whatsoever without the expresswritten permission of GIA.Printed in the United States.Reprinted 2005

Table of ContentsIntroduction 1Agate 2Alexandrite 4Almandite 6Amber 8Amethyst 10Aquamarine 12Bloodstone 14Carnelian 16Cat’s-Eye 18Black Chalcedony 20Chalcedony 22Citrine 26Coral 28Demantoid 32Emerald 34Hematite 38Hessonite 40Iolite 42Ivory 44Jade (Jadeite) 46Jade (Nephrite) 50Kunzite 54Lapis Lazuli 56Malachite 58Malaya Garnet 60Moonstone 62Morganite 64Onyx and Sardonyx 66

Opal 68Pearl and Cultured Pearl 72Peridot 76Pyrope 78Rhodolite 80Rose Quartz 82Ruby 84Sapphire 88Shell 92Smoky Quartz 96Spessartite 98Spinel 100Star Ruby 102Star Sapphire 106Tanzanite 110Tiger’s-eye 112Topaz 114Tortoise Shell 118Tourmaline 120Tsavorite 124Turquoise 126Zircon 130

1

IntroductionFor centuries, artists and poets have used images of colored stones to express love, passion, andpower. People in every era and from all walks of life have adorned themselves with the dra-matic, radiant grace of colored stone jewelry.

This volume, The Essential Colored Stone Reference Guide (The Reference Guide for short),is written in lively, understandable language, with stunning illustrations and an easy, look-it-upformat.

Convenient organization makes it easy to put The Reference Guide to work for you. Entriesare listed alphabetically by common name. Applicable species, variety, and group names arelisted below the heading. You can refer to the Table of Contents if you want to go directly to aspecific listing.

Each entry provides clear, practical information that you can use to enrich your sales pre-sentations. For example, a “Care and Cleaning” chart lists common cleaning methods and therelative safety of each method for that particular gem. Common synthetics, treatments, and imi-tations are listed as appropriate, too.

Another feature of each entry is the list of alternative gems at the end of each section. Thiswill be useful to you when, for example, you’re talking with a customer who loves purple, butisn’t sure she wants an amethyst.

Besides practical information, some gem entries include interesting lore. For example, didyou know that amber is sometimes called “Gold of the North,” or that emerald was one ofCleopatra’s favorite gems? There’s also a list of the places considered sources of each gem.These bits of information can enhance your presentation and make the gem more interesting toyour customer.

The Reference Guide covers gems you’re likely to see in jewelry stores, catalogs, and other retailsettings. But the world of colored stones is vast and varied, and even a guide like this can’t possi-bly include every gem or every property of a given gem. GIA also offers the more advanced—andmore technical—Gem Reference Guide, which discusses the gems covered here as well as less-well-known gems, and offers more scientific detail on each gem.

The Essential Colored Stone Reference Guide is your key to the product knowledge youneed to sell color with style and confidence. When new colored stone jewelry appears in yourinventory, look it up in the guide. And by all means, use The Reference Guide to help youanswer customer questions. You’ll find that with its beautiful photographs and friendly format,it’s a powerful sales tool.

©1999 by GIA. All rights reserved.

AgateAgate/Chalcedony

2

Agate is a fine-grained chalcedony quartz and one of the first gem materi-als known. Its history goes all the way back to the ancient Egyptians, whofirst used it for adornment more than 3,000 years ago. Ancient cultures usedit in amulets and talismans. They believed that it provided the wearer witha bold heart and pleasant dreams. Roman artisans carved seals from it.Nineteenth century Victorians used it to create beautiful cameos.

The characteristic that sets agate apart from other chalcedonies is its appear-ance: It boasts dramatic curved or angular stripes, or bands of color. These dis-tinctive markings vary widely in color and translucence. The patterns in someagates look like moss, ferns, and trees—even entire landscapes. Others havesimple striped patterns of two or more colors. Besides cameos, modern cutting

styles that make the most of agate’s unique appearanceinclude cabochons, beads, and carvings.

Fire agate is a relative newcomer to the agate family,discovered in the 1940s. Its mineral layers cause lightinterference and give it a shimmering iridescenceagainst its brown bodycolor.

SourcesBrazilIndiaMadagascarMexicoUnited StatesUruguay

Hardness & ToughnessHardness 61/2 to 7 on Mohs scaleToughness Good

Carved agate

VarietiesEye agate, orbicular agate Banded in concentric ringsLandscape agate Chalcedony with colored pat-

terns resembling a landscapeFire agate Iridescent inner layersDendritic agate, scenic agate Colorless or white, translucent,

with markings resembling trees,ferns, moss, or landscapes

Iris agate Semitransparent to translucent,with iridescent colors

StabilityEnvironmental Factor Reaction

Heat Color may changeLight StableChemicals Attacked by hydrofluoric acid;

nitric acid may attack dye

TreatmentsTreatment Description Purpose Stability Prevalence

Dyeing

Heating Improves color Permanent Common

Care and CleaningType of Cleaning Advisability

Steam cleaning Not recommendedUltrasonic cleaning Not recommendedWarm, soapy water Safe

3

Gray SouthAmerican agate isdyed with inor-ganic dye. Layersabsorb dye differ-ently dependingon porosity.

Improves color,improves band-ing

Generally stableunder normal con-ditions. May fadeor be removed bychemicals.

Common

Landscape agate

Iris agate

Producesorange ororangy redcolor in yellowto brown agate

Landscape agate

AlexandriteAlexandrite/Chrysoberyl

4

Alexandrite is a rare chrysoberyl variety with chameleon-like qualities. Itscolor is a lovely green in daylight or fluorescent light, but it changes to brown-ish or purplish red in the incandescent light from a lamp or candle flame.

Alexandrite’s dramatic color change is sometimes described as “emeraldby day, ruby by night.” Other gems also change color in response to achange in light source, but this gem’s transformation is so striking that thephenomenon itself is often called “the alexandrite effect.”

Abundant alexandrite deposits were first discovered in 1830, in Russia’sUral Mountains. Those first alexandrites were of very fine quality, and dis-

played vivid hues and dramatic color changes. The gemwas named after the young Czar Alexander II, and itcaught the country’s attention because its red and greencolors mirrored the Imperial Russian flag.

The spectacular Ural Mountain deposits didn’t lastforever, and now most alexandrite comes from SriLanka, East Africa, and Brazil. The newer deposits con-tain some fine-quality stones, but many possess lessprecise color change and muddier hues than the nine-teenth century Russian alexandrites. You’ll still findsome of the famed Ural Mountain alexandrites in estatejewelry. They remain the quality standard for this phe-nomenal gemstone.

Because of its scarcity, especially in larger sizes,alexandrite is a relatively expensive member of thechrysoberyl family. It shares its designation as a Junebirthstone with cultured pearl and moonstone.

SourcesBrazilEast AfricaRussiaSri Lanka

Hardness & ToughnessHardness 81/2 on Mohs scaleToughness Excellent


Heat StableLight StableChemicals None


Ultrasonic cleaning Usually safeSteam cleaning Usually safeWarm, soapy water Safe

ImitationsSynthetic color-change sapphireSynthetic color-change spinel

SyntheticsFluxCzochralski

AlternativesColor-change garnetColor-change sapphire

5

Alexandrites in incandescent light

Alexandrites in fluorescent light

AlmanditeAlmandite/Garnet

6

Almandite is probably one of the most familiar of theclosely related species that make up the garnet group.It’s a fairly common red garnet, with a color range fromorangy red through red to reddish purple.

Almandite was named for Alabanda, an ancientAsian town and an active gemstone trading and fashion-ing center. Ancient Romans often fashioned almanditegarnets as thin, hollowed cabochons to bring out theintensity of their color.

Other species in the garnet group come in a variety ofhues, from browns and oranges to vibrant greens. As farback as 3100 BC, Egyptians along the Nile worked gar-net into beads and inlays. Noah is said to have recog-nized garnet’s inner fire and used it as a lamp on thebow of the ark. Garnets of all species, including alman-dite, are considered January birthstones.

SourcesBrazilIndiaMadagascarPakistanSri LankaUnited States

Hardness & ToughnessHardness 7 to 71/2 on Mohs scaleToughness Fair to good


Heat Abrupt temperature changes likelyto cause fracturing

Light StableChemicals None, except concentrated

hydrofluoric acid


Ultrasonic cleaning Usually safeSteam cleaning NeverWarm, soapy water Safe

ImitationsGarnet-and-glass doublet

AlternativesHessonite garnetMalaya garnetPyrope garnetRhodolite garnetRubySpessartite garnetSpinelTourmaline

7

Amber

8

Amber belongs to the category of organic gems—the products of livingorganisms and biological processes. Amber formed millions of years ago,when sap from ancient trees hardened and fossilized. Stone Age people dis-covered these golden jewels along the shores of the Baltic Sea, and theybecame perhaps the earliest and most consistently popular ornamental gems.

Scientists and collectors treasure amber that contains suspended animal orplant fragments: Fossilized bits of once-living things that were trapped in thehardening amber millions of years ago, creating a fascinating time capsule.

Some types of amber are found in the ground. Other types have beenfreed and carried by tides and end up on beaches or near-shore areas. The

Baltic coast bordering Germany, Poland, and Russia isstill a source of amber, which is sometimes called “goldof the North.” Amber’s warm luster is featured in beads,carvings, pendants, and cabochon rings, as well as dec-orative items like cups, bowls, snuff boxes, and umbrel-la handles.

Amber’s colors range from whites, yellows, andoranges to reds and browns. Clear material is preferredin the US, cloudy in Europe and North Africa. Heatingcloudy amber in oil clarifies it. Heat treatment can alsoproduce disk-like stress fractures and create an attrac-tive product called sun-spangled amber.

SourcesDominican Republic

GermanyMexicoPolandRussia

Currently the major source

Hardness & ToughnessHardness 2 to 21/2 on Mohs scaleToughness Poor


Heat Burns at low temperaturesLight May darken with ageChemicals Attacked by acids, caustics, alcohol,

gasoline

TreatmentsTreatment Purpose Stability Prevalence Detection

Heating in oil Stable Occasional May be detectable

Heating Lightens color Stable Occasional Undetectable

Stable Common May be detectable

Dyeing Darkens color May fade Occasional May be detectable


Steam cleaning NeverUltrasonic cleaning NeverWarm, soapy water Safe, but hard brushes may scratch

ImitationsAmbroid (reconstructed or pressed amber)Copal (a natural resin, younger than amber)PlasticYellow glass

9

Produces sunspangles

Clarifies cloudyamber

Close-up of spider trapped in amber

Amber pendant showing sun spangles

Close-up of insect trapped in amber

Heating (some-times with oil)

AmethystAmethyst/Quartz

10

Amethyst has been the most prized member of the quartz family for cen-turies. Early Greek legends, and its wine-purple color, associated amethystwith Bacchus, the god of wine. Other legends led to beliefs that amethystgems kept their wearers clear-headed and quick-witted in battle and in theirbusiness affairs. It’s no wonder that fine amethyst adorns the fingers of bish-ops and the coronation regalia of British royalty.

Russia was once the main source of amethyst, but near the turn of the twen-tieth century, new deposits were discovered in South America. After that, itbecame more widely available, but no less treasured. Amethyst comes in arange of sizes, and the color selection ranges from palest lilac to rich purple.

Experts consider African amethyst’s royal purple withreddish overtones to be the gem’s finest color.

A closely related quartz variety called ametrine con-tains a striking mixture of two contrasting quartzes—purple amethyst and yellow citrine. Ametrine depositsare found in Brazil and Bolivia.

Amethyst is the birthstone for February.

SourcesBrazil Major sourceIndiaNamibiaSri LankaUnited StatesUruguayZambia

Hardness & ToughnessHardness 7 on Mohs scaleToughness Good


Heat Abrupt temperature change may fracture stone, can alter colorLight Some amethyst may fadeChemicals Damaged by hydrofluoric acid, ammonium fluoride, alkalies


Heating Excellent Occasional Undetectable


Steam cleaning Not recommendedUltrasonic cleaning Usually safeWarm, soapy water Safe

ImitationsGlassPurple synthetic corundumAssembled stone (synthetic spinel triplet)

SyntheticsHydrothermal

AlternativesIoliteRhodolite garnetSapphireSpinelTanzaniteTopazTourmaline

11

Lightens coloror producescitrine or greenquartz

Carved amethyst

Contemporary amethyst anddiamond pendant

Ametrine

AquamarineAquamarine/Beryl

12

Aquamarine’s cool blue hues are reflected in its name, which comes fromthe Latin for “sea water.” Medieval sages prescribed water touched by aqua-marine for a host of ills, including those affecting the eyes and lungs. Theypromised the virtues of insight and foresight to the gem’s wearers.

Aquamarine crystals can grow to huge sizes, and are usually blessed withexcellent clarity. Gem bodycolors range from greenish blue to blue-green inlight tones. Usually, the color is more intense in larger stones, but someaquamarine from Africa displays deeper blues in faceted stones of less than5 cts. Brazil supplies the most aquamarine to the modern market.

Like emerald, aquamarine is a member of the berylspecies. The gem is March’s birthstone.

SourcesAustraliaBrazil Major sourceChinaKenyaMadagascarMozambiqueNigeria Known for intense color in smaller

sizes (under 5 cts.)PakistanUnited StatesZambia



Heat Exposure to heat not recommendedLight StableChemicals Attacked by hydrofluoric acid


Heating Very good Routine Undetectable


Ultrasonic cleaning Usually safe, unless stone contains feathers or liquidinclusions

Steam cleaning Usually safe, unless stone contains feathers or liquidinclusions

Warm, soapy water Safe

ImitationsGlassSynthetic spinel

AlternativesBlue topazSapphireSpinelTanzaniteTourmaline

13

Removes yel-low, resultingin purer bluecolor

A 32.10-ct. heart-shapedaquamarine from Brazil

Flower brooch featuring aquamarine

Aquamarine crystal from Afghanistan weighing over100 cts.

BloodstoneBloodstone/Chalcedony

14

Bloodstone is an opaque to semitranslucent variety ofchalcedony. Its bold coloring—dark green flecked withred—has intrigued people for centuries. The ancientGreeks named it heliotrope (“sun-turner”) because theyobserved that it flashed scarlet when they lowered itinto water and pointed it toward the sun. Many peoplethought it colored water red for the same reason.Citizens of Medieval and Renaissance Europe honoredbloodstone as a talisman that stirred passion, stoppedbleeding, and brought healing.

Rich men in the time of King Solomon prized thegem for use in their seal rings, and it’s still set in men’sjewelry today. Bloodstone is also popular in Christianjewelry because its distinctive pattern reminded earlyChristians of the blood of Christ at the foot of the cross.

Bloodstone is the alternate birthstone for March.

SourcesAustraliaBrazilChinaIndiaUnited States


StabilityEnvironmental Factor ReactionHeat Color may changeLight StableChemicals Attacked by hydrofluoric acid


Ultrasonic cleaning Not recommendedSteam cleaning Not recommendedWarm, soapy water Safe

15

CarnelianCarnelian/Chalcedony

16

Carnelian is a semitransparent to translucent variety of chalcedony. Gemspecialists believe it was named after the kornel cherry, which grows in thesame warm shades as the gem: Yellowish orange to orangy red to brownishorange. It’s often fashioned into beads or cameos to show off its color.

Ancient civilizations believed that carnelian transformed poor or timidspeakers into eloquent ones. Carnelian’s history began in India, where it wasmined as early as the fourth century BC.

SourcesBrazilIndiaUruguay



Heat Color may changeLight StableChemicals Attacked by hydrofluo-

ric acid


Heating Improves color Stable Common Undetectable



ImitationsGlassPlastic

AlternativesAmberFire opalJadeSard chalcedony

17

Carnelian intaglio ring

Carnelian intaglio

Roman carnelian intagliofrom the first century BC

Cat’s-EyeCat’s-Eye/Chrysoberyl

18

This gem, with its band of reflected light across the middle, has alwaysreminded observers of the eye of a cat. The cat’s-eye effect, also called cha-toyancy, is caused by parallel needle-like inclusions within the stone. Thegem was once known as cymophane—Greek for “waving light.” In somecultures, its distinctive appearance made it the preferred treatment for allsorts of eye ailments.

Chatoyancy appears in other gemstones, but fine-quality cat’s-eyechrysoberyl sets the standard. It’s also the most valuable cat’s-eye stone. It’sdurable as well as attractive, which makes it popular in men’s rings, cufflinks,

and tie tacks. The cabochon cut brings out its cat’s-eyeeffect to best advantage.

Cat’s-eye chrysoberyl ranges from brown to greenishyellow. The finest quality specimens boast a goldencolor, with bands that span the entire length of the gem.The bands themselves are distinct, silvery-white, andstraight.

The chatoyant band in cat’s-eyes will appear to blinkwhen you hold the stone between two light sources,then rotate it. As you turn the stone, the eye splits intotwo bands that move apart, then back together. Thiseffect is called “opening and closing.”

Cat’s-eyes display another impressive effect, calledmilk and honey. With the light positioned perpendicularto the chatoyant band, the side nearest the light showsthe stone’s original bodycolor while the other side has amilky appearance.

SourcesBrazilEast AfricaSri Lanka

Hardness & ToughnessHardness 81/2 on Mohs scaleToughness Excellent to good


Heat StableLight StableChemicals None



ImitationsCat’s-eye glass

AlternativesCat’s-eye quartzCat’s-eye tourmalineTiger’s-eye quartz

19

Cat’s-eye chrysoberyl mounted in art deco pin

Cat’s-eye chrysoberyl set in art deco-style platinum ring with diamonds

72.68-ct. cat's-eye chrysoberyl cabochon with a317.7-ct piece of rough from Brazil

Black Chalcedony

20

Natural black chalcedony is extremely rare. The jewelry industry common-ly calls dyed black chalcedony, which is more common, “black onyx.” Thisalways-stylish gem was prominent in the Art Deco jewelry of the 1920s and1930s. Jewelry designers of the time often set it in platinum with diamonds,or with the colorless quartz variety known as rock crystal.

Because “basic black” is always in style, so is black chalcedony. It hasthe added advantages of good durability, low cost, and availability in analmost unlimited range of sizes. It’s one of the most popular gems for beads,cabochons, tablets, inlays, and carvings. You’ll often find this stone in men’s

jewelry.Black chalcedony is also commonly used as a back-

ing for opal doublets and triplets. In doublets, piecesof opal too thin to use alone are often cemented to atablet of black chalcedony. This dramatizes the opal’splay of color and gives strength to the assembledstone. A triplet requires the addition of a protective topmade of rock crystal quartz or some other hard, color-less material.

SourcesBrazil Gray chalcedony, later dyed black


StabilityEnvironmental Factor ReactionHeat Color may changeLight StableChemicals Attacked by hydrofluoric acid; nitric acid may

attack dye





AlternativesHematiteJadeite jadeNephrite jadeOnyx

21

Boiling in asolution of sugarand water, thensoaking in sulfu-ric acid. Usuallydescribed as“dyeing.”

Produces blackcolor in graychalcedony

Stable undernormal condi-tions

Routine.Virtually allblack chal-cedony is dyed.

No tests.Treatment isassumed.

Chalcedony

22

Chalcedony is one of the world’s oldest, most abundant, and most populargems. It was named for the ancient Turkish seaport of Chalcedon (nowcalled Kadikoy). Many cultures throughout history have used it for a vari-ety of purposes. Many considered it a powerful talisman. In the third andfourth centuries, Greek sailors wore chalcedony amulets as protectionagainst drowning. As late as the 1700s, many Europeans believed chal-cedony would drive away ghosts and bad spirits.

Chalcedony is fairly affordable, and it comes in an incredibly wide rangeof colors and patterns. These two factors make it very popular with gem andmineral collectors. In jewelry, you’ll see it most often as beads, cabochons,tablets, and carvings. Imaginative designers use chalcedony in some of themost cutting-edge creations available on the market.

Mineralogists consider chalcedony a variety of quartz, but gemologistsand gem professionals treat the two as separate species. The differencebetween them is that quartz occurs in large crystals, while the individual

crystals that make up chalcedony are so small that ittakes very high magnification to see them.

SourcesSee Agate, Bloodstone, Carnelian, and Onyx andSardonyx for sources of those gems.Australia ChrysopraseBrazil Many varietiesCzech Republic ChrysopraseGermany JasperIceland Milky chalcedonyIndia Chrysoprase, milky chalcedonyItaly JasperMexico Chrysocolla-in-chalcedonyRussia Jasper, milky chalcedonyScotland JasperUnited States Amethystine chalcedony, chryso-

colla-in-chalcedony, chrysoprase,jasper, milky chalcedony

Uruguay Sard

23


VarietiesVariety Name Appearance and Comments

Agate Translucent to opaque, with curved or angular colorbanding; also patterns such as “moss” and “land-scape.” For additional information, see Agate.

Amethystine chalcedony Semitranslucent to opaque purple. Often marketed as“purple agate” or under the trade name “damsonite.”

Bloodstone Semitranslucent to opaque, dark green with red tobrownish red spots. For additional information, seeBloodstone.

Carnelian Semitransparent to translucent, yellow-orange toorangy red, often slightly brownish. For additionalinformation, see Carnelian.

Chrysocolla-in-chalcedony Translucent to semitranslucent, intense light blue orblue-green. Can resemble fine turquoise. One of themost valuable chalcedony vari-eties.

Chrysoprase Semitransparent to translucent,light to medium yellowish green.The name comes from Greekwords meaning “golden apple,”and is ethically used only for natu-ral-color (not dyed) material.

Dendritic agate Chalcedony with dark inclusionsresembling tree branches.

Fire agate Semitranslucent to opaque, withiridescent colors against a brownbodycolor.

Iris agate Semitransparent to translucent, withiridescent colors (phenomenon bestseen on thin slices in transmittedlight)

Jasper Opaque; any color or combinationof colors except solid black ormaterial known by another name(agate, black chalcedony, carnelian,and so forth). Opaque whitishjasper is often dyed blue to imitatelapis lazuli.

Chrysocolla-in-chalcedony

24

Milky chalcedony Semitransparent to translucent, nearly colorless towhite or light gray. Often sold as an alternative formoonstone.

Onyx Translucent to opaque, with straight, parallel bands ofdifferent colors. For additional information, see Onyxand Sardonyx.

Sard Semitransparent to translucent, dark brown, brownishorange, or brownish red (darker and less saturatedcolor than carnelian).

Sardonyx Onyx with sard colors alternating with either white orblack. For additional information, see Onyx andSardonyx.


Heat Color may change, especially if dyedLight StableChemicals Attacked by hydrofluoric acid; nitric acid may attack

dye in treated material

Chrysoprase chalcedony


Dyeing Common

* If there is any doubt, send the gem to a gemological laboratory for verification. Even then,some colors are not detectable.




AlternativesAmberHematiteJadeite jadeLapis lazuliMalachiteMoonstoneNephrite jadeRose quartzShellTiger’s-eyeTurquoise

25

Produces awide variety ofcolors

Generally sta-ble under nor-mal conditions

Some colorsdetectable by atrained gemolo-gist or gemologi-cal laboratory.*Often assumedbecause of unnat-ural color.

Dendritic chalcedony

CitrineCitrine/Quartz

26

Citrine is one of the US birthstones for November (the other is topaz). It’s aquartz variety, and the top-selling transparent gem in the yellow to orangecolor range. Its name was derived from the Latin word citrus, meaning “cit-ron” (a fruit closely related to the lemon). This gem combines a warm,attractive color with good wearability and a moderate price—an unbeatablecombination for many customers.

Citrine comes in an exceptionally wide range of sizes. The largest trans-parent faceted gem on record (in terms of dimensions and volume) is a cit-rine. It measures 25.5 cm ˘ 14.1 cm ˘ 10.0 cm (9.9 in. ˘ 5.5 in. ˘ 3.9 in.), andweighs 19,548 cts. (3.9 kg/8.6 lb.). Jewelry-sized citrines are readily avail-able in weights of up to 20 cts. and more.

Most citrine is faceted in traditional rounds and fancy shapes, but you’llalso find it fashioned into more unusual cuts and carvings. Leading jewelrydesigners use citrine alone, in combination with diamonds, and in multicol-

ored creations alongside gems with contrasting colors—amethyst, aquamarine, blue topaz, and others.

Before the development of modern gemology, citrinewas traditionally confused with topaz because of theirsimilar colors.

SourcesBoliviaBrazilSpain



Heat High heat can cause color loss; sudden or extremetemperature change can cause fracturing

Light StableChemicals Soluble in hydrofluoric acid and ammonium fluoride;

very slightly soluble in alkalis


Heating


Ultrasonic cleaning Usually safeSteam cleaning Not recommendedWarm, soapy water Safe

ImitationsGlassPlasticSynthetic hydrothermal quartzSynthetic sapphireSynthetic spinel

AlternativesAmberCarnelianChrysoberylMalaya garnetSapphireSmoky quartzSpessartite garnetTopazTourmaline

27

6.20-ct. citrine from Brazil

Carved citrine

Citrine Quartz from Brazil

Produces color—changesamethyst to cit-rine

Permanent undernormal condi-tions

Routine. Mostcitrine is pro-duced by heattreatingamethyst.

Undetectable.Treatment isassumed.

Coral

28

For thousands of years, cultures around the world haveprized coral as a gem and credited this product of the seawith magical powers. First century Romans used it toward off evil and to impart wisdom. It’s still worn inmodern-day Italy as protection against the “evil eye”and as a cure for sterility.

There are two basic types of gem coral. One typecomes in a variety of lighter shades: White, cream orpink, various shades of red or orange, and occasionallyblue, purple, or light grayish violet (known as “laven-der” in the trade). The other coral type is black, darkbrown, or sometimes light brownish yellow (oftencalled “golden”).

All coral is composed of the remains of skeleton-likesupport structures that were built by colonies of tinymarine animals. These coral polyps, as they’re called, areclose relatives of the more familiar coral reef builders.

Coral jewelry, in the form of beads, cabochons, andespecially small carvings and cameos, has been popularin Europe since Roman times. Its popularity is strong inboth North and South America. At one time, Asiancountries used coral more often for large carvings, butWestern influences prompted increased production andpopularity of coral jewelry in the twentieth century.

World demand for coral jewelry remains high, eventhough a number of factors have combined to drasticallyreduce the supply of new material in recent decades.These factors include pollution, over-harvesting, andincreasing national and international environmental pro-tection efforts.

For centuries, the most prized qualities of coral camefrom the Mediterranean Sea, along the coasts ofAlgeria, France, Italy, Morocco, Spain, and Tunisia.

Unfortunately, pollution and depletion have devastated thesewaters. Australia—another once-important source—now pro-hibits the export of all native coral. The state of Hawaii pro-tects black “King’s” coral as an endangered species. Allthese factors limit modern supplies of coral, but the avail-ability of high-quality older pieces guarantee it a perma-nent place in the antique market.

SourcesJapanMalaysiaPhilippines

Hardness & ToughnessHardness 3 to 4 on Mohs scaleToughness Fair to good


Heat Blackens or burns if exposed to theflame of a jeweler’s torch

Light Generally stable; dyed materialmay eventually fade

Chemicals Easily attacked by acids and otherchemicals

29

Chimera bracelet bangle by Cartier (not signed) ofcarved coral set with diamonds in platinum

Red coral

30


Dyeing Occasional

Stable Common

* If there is any doubt, send the gem to a gemological laboratory for verification.

Deepens orchanges color,usually to pinkor red, but anycolor is possi-ble

Dye can beaffected orremoved bysolvents, andcan fade underprolongedexposure tostrong light

Might bedetectable by atrained gemolo-gist or gemo-logical labora-tory*

Fills and hidescavities andfractures

Stable undernormal condi-tions, but canbe damaged ordestroyed byhigh heat andsolvents

Common inlow-qualitymaterial

Detectable by atrained gemolo-gist or gemo-logical labora-tory

Impregnationwith epoxyresin or glue-like sustances

Bleaching inhydrogen per-oxide solution

Produces“golden” colorin black coral

Detectable by atrained gemolo-gist or gemo-logical labora-tory


Ultrasonic cleaning RiskySteam cleaning NeverWarm, soapy water Safe

ImitationsGlass Plastic

AlternativesAmberCarnelianChalcedonyCultured pearlJadeite jadeNephrite jadeRose quartzShell

31

Carved and rough coral

Different types and colors of coral

Enamel and coral beads torsade necklace

DemantoidDemantoid/Andradite/Garnet

32

Demantoid means “diamond-like” in Dutch, the language of Renaissancediamond cutters. Its name reflects the fact that, while demantoid is muchsofter than diamond, its dispersion is higher, so its flashes of rainbow colorare very noticeable, especially in lighter-colored stones. This lush greengem is a variety of andradite and a member of the garnet group.

Demantoid displays intense color in the green to yellow-green range.Under the microscope, fine demantoid has another telltale signature: Itsclassic “horse-tails.” They are wisps of long, golden, fiber-like inclusionsthat radiate from a central point.

Demantoid was discovered in Russia’s gem-rich UralMountains in 1868. Tiffany and Company’s chief gembuyer, George Kunz, fell in love with the newly discov-ered gem, and the company bought up all that theycould get. Tiffany marketed it as an appealing emeraldalternative. Even though it was rarely available in sizeslarger than 2 cts., demantoid adorned much Victorianjewelry crafted between 1895 and 1915.

The historic Russian source doesn’t yield muchdemantoid any more. In fact, the scarcity of fine-quali-ty demantoid has made it a prized collector’s stone.Recent discoveries in Namibia, however, haveincreased the availability.

Demantoid joins the rest of the garnet group as aJanuary birthstone.

SourcesNamibiaRussiaZaire

Hardness & ToughnessHardness 61/2 to 7 on Mohs scaleToughness Fair to good


Heat Abrupt temperature changes likelyto cause fracturing

Light StableChemicals Attacked by hydrofluoric acid

Care and CleaningType of Cleaning AdvisabilityUltrasonic cleaning Usually safe, risky if contains

liquid inclusionsSteam cleaning NeverWarm, soapy water Safe

ImitationsColored CZ Colored YAGGarnet-and-glass doublet

AlternativesEmeraldGreen sapphireGreen zirconPeridotTourmalineTsavorite garnet

33

Close-up of the horsetail inclusion in a demantoid

Visible horsetail inclusion in a demantoid garnet

EmeraldEmerald/Beryl

34

Emerald’s lush green has soothed souls and excited imaginations sinceantiquity. Its name comes from the ancient Greek word for green, “smarag-dus.” Rome’s Pliny the Elder described emerald in his Natural History, pub-lished in the first century AD: “…nothing greens greener” was his verdict.He described the use of emerald by early lapidaries, who “have no bettermethod of restoring their eyes than by looking at the emerald, its soft, greencolor comforting and removing their weariness and lassitude.” Even today,the color green is known to relieve stress and eye strain.

The first known emerald mines were in Egypt, dating from at least 330BC into the 1700s. Cleopatra was known to have a pas-sion for emerald, and used it in her royal adornments.

Emeralds from what is now Colombia were part ofthe plunder when sixteenth-century Spanish explorersinvaded the New World. The Indians had already beenusing emeralds in their jewelry and religious cere-monies for 500 years. The Spanish, who treasured goldand silver far more than gems, traded emeralds for pre-cious metals. Their trades opened the eyes of Europeanand Asian royalty to emerald’s majesty.

Emerald is often mined and sold under peril—thenatural resource Colombians cherish is also coveted byunderworld drug traders. The availability of fine-qualityemerald is limited, and emerald was plagued in the late1990s by negative publicity about treatments commonlyused to improve its clarity.

Emerald is the most famous member of the berylfamily. Legends gave it the power to make its wearermore intelligent and quick-witted. It was once alsobelieved to cure diseases like cholera and malaria. Itscolor reflects new spring growth, which makes it theperfect choice of a birthstone for the month of May. It’salso the gemstone for twentieth and thirty-fifth weddinganniversaries.

35

SourcesAfghanistanBrazilColombia One of the largest commercial producers: Fine

Colombian emeralds are highly regarded for theirexcellent color

PakistanRussiaZambia A major commercial source: Zambian emeralds tend to

have good clarityZimbabwe The Sandawana Valley is a famous source

Hardness & ToughnessHardness 71/2 to 8 on Mohs scaleToughness Poor to good


Heat May cause fracturesLight Fracture fillings may dry out or

alter under intense lightChemicals Fracture fillings may be affected

by any type of chemical, emeralditself is resistant to all acids excepthydrofluoric

Emerald cross recovered from NuestraSenora de Atocha Galleon

36

TreatmentsTreatment Description Purpose Stability Prevalence

Fracture Filling Not permanent Routine

Dyeing Not permanent Rare

Coating Not permanent Rare

Care and CleaningMost emeralds have been fracture-filled. An emer-ald’s appearance may change over time due to theinstability of its filling material. Depending upontheir condition, emeralds may be retreated by anexperienced professional.

Type of Cleaning Advisability

Steam cleaning NeverUltrasonic cleaning NeverWarm, soapy water Usually safe. Avoid vigorous scrubbing

Filling surface-reaching frac-tures with col-orless oils orresins. Simplycalled “oiling”in the tradewhen colorlessoils are used.

Improves clari-ty, improvescolor

Adding col-orant to the oilsor resins usedin the fracture-filling process

Improves emer-ald color, giveslight-coloredberyls an emer-ald green color

Covering alight-coloredberyl with agreen plastic

Creates anemerald imita-tion

ImitationsGreen glassSynthetic spinel triplet

SyntheticsFluxHydrothermal

Alternatives AlexandriteDemantoid garnetDiopsideJadeitePeridotSapphireTourmalineTsavorite garnetZircon

37

Colombian rough and cut emeralds

Hematite

38

Hematite’s shiny metallic luster and dark gray to black color give it a spe-cial beauty and appeal that’s shared by few other stones. It’s inexpensive,and available in a wide range of sizes, so it’s a traditional favorite for men’srings—especially when it’s engraved with a warrior’s head or animal motif.It’s also widely used for pendants as well as bead necklaces and bracelets.

Hematite has the highest density (weight-to-size ratio) of any commonlyavailable natural gem. This gives hematite jewelry a weighty feel and anaura of value. Its high density has a down side for some wearers of hematiteearrings, though: Large pendant and hoop styles are too heavy to wear com-

fortably for long periods.Hematite is composed of iron oxide, so it’s chemi-

cally the same as common rust. The name comes fromthe Greek word haima, which means “blood”—refer-ring to the red color of the mineral in its powder form.Hematite’s name means, literally, “blood stone.”

People in ancient mideastern cultures believed thathematite would ensure victory in lawsuits and favorablejudgments from kings and others in authority. DuringRoman times, the gem was associated with Mars, god ofwar: It was believed to protect a warrior who rubbed iton his body. Native Americans also used powderedhematite as a pigment for war paint.

SourcesEnglandNorwaySwedenUnited States

Hardness & ToughnessHardness 51/2 to 61/2 on Mohs scaleToughness Fair


Heat May become magneticLight StableChemicals Soluble in hydrochloric acid


Ultrasonic cleaning SafeSteam cleaning SafeWarm, soapy water Safe

ImitationsImitation hematite—usually made mostly of compressediron, and often stamped with an intaglio design. Oncemarketed as “hemetine,” but that trade name wasruled misleading by the FTC.

AlternativesBlack chalcedonyCultured pearlJadeite jadeNephrite jade

39

HessoniteGarnet/Grossularite/Hessonite

40

Hessonite is a variety of grossularite garnet. Its closerelative, tsavorite, is also a grossularite variety. Buthessonite’s warm brownish yellows, brownish oranges,and brownish reds make quite a contrast to tsavorite’scool green. Because of hessonite’s color, as well as itshistoric connection with the spice-producing countryof Sri Lanka, this garnet is also known as “cinnamonstone.”

SourcesBrazil Canada Madagascar Mexico Sri LankaTanzania US



Heat Abrupt temperature change likelyto cause fracturing



Ultrasonic cleaning Usually safe, unless liquid inclu-sions are present

Steam cleaning NeverWarm, soapy water Safe

AlternativesAlmanditeCitrineFire opalSapphireSpessartiteTopazZircon

41

Iolite

42

Iolite gets its name from the Greek word for violet, andlike that flower, its cool shades range from light to darkblue and violet. It’s a transparent to translucent gemthat’s strongly pleochroic. This means that it shows dif-ferent colors from different viewing angles. From someangles, blue iolite can actually appear colorless. Otherpleochroic colors include gray, violet, or yellow. Thisoptical property allows the gem to act as a strong light-polarizing filter, a feature that Viking navigators founduseful. To locate the sun—and chart their position—onovercast days, they viewed the sky through a thin pieceof iolite.

SourcesBrazilIndiaMadagascarNamibiaNorwaySri LankaTanzania

Hardness & ToughnessHardness 7 to 71/2 on Mohs scaleToughness Fair


Heat Can be damagedLight StableChemicals Attacked by acids


Ultrasonic cleaning RiskySteam cleaning RiskyWarm, soapy water Safe

ImitationsGlass

AlternativesBlue topazSapphireTanzanite

43

Ivory

44

Ivory is an organic material that has been part of human art and culture forthousands of years. It has always symbolized the strength, life force, andmajesty of nature, and ivory objects served ceremonial, ornamental, andutilitarian purposes for most of the great civilizations. In Europe, archaeol-ogists unearthed ivory carvings and artifacts that are as much as 30,000years old. The Egyptians were crafting exquisite ivory ornaments by 8000BC. Its easy workability and color palette—ranging from soft or radiantwhites to warm light or golden brownish yellows—made ivory a prizedmedium for artisans, gem carvers, and jewelry designers.

Today, ivory is one of the world’s most controversial gem materials. Itcomes from the tusks or teeth of certain mammals, and those mammals mustdie in order to yield their treasure. The most familiar ivory source is the ele-phant. Others include the hippopotamus, narwhal, sperm whale, walrus, and

warthog. Most are endangered species.International prohibitions exist (under the UN

Convention on the International Trade in EndangeredSpecies of Wild Flora and Fauna [CITES]) against tradein ivory. More than 100 nations are parties to CITES,and most of them have enacted laws to reinforce theban. Beyond this, environmental and animal-rightsactivists militantly oppose commerce in ivory, and mostconsumers shun it as well. Despite all this, there’s still astrong market for ivory, which is now supplied almostexclusively by criminal means.

A limited alternative to ivory is fossil ivory, whichcomes mostly from the remains of woolly mammothsthat inhabited the northern hemisphere more than10,000 years ago. Its main source is the RussianSiberian region. There’s also a legitimate collector’smarket in antique ivory. Unfortunately, some dishonesttraders use treatments to artificially “age” new ivory,thus avoiding the legal prohibitions.

Hardness & ToughnessHardness 2⁄ to 2fl on Mohs scaleToughness Fair


Heat Causes shrinkage, cracking, anddiscoloration

Light Yellows with ageChemicals Attacked by many chemicals; soft-

ened by nitric and phosphoric acid


Bleaching Stable Common Undetectable

Dyeing Stable Common

Heating Stable Undetermined


Ultrasonic cleaning NeverSteam cleaning NeverWarm, soapy water Safe


AlternativesChalcedonyCultured pearlJadeite jadeNephrite jadeShell

45

Lightens orremoves stains

Can impart anycolor, but usuallydone to simulatethe appearance ofantique ivory

Usually unde-tectable unlessthe color isunnatural inappearance

Darkens thecolor to simulatethe appearance ofantique ivory

Usually unde-tectable

Ivory doctor’s doll

Jade [Jadeite]

46

There are two different gem minerals that are correctly called jade, andjadeite is one of them. (The other is nephrite.) Jadeite comes in a wide rangeof attractive colors: Many shades of green, yellow, and reddish orange, pluswhite, gray, black, brown and lavender (which often refers to light purple orlight grayish violet). The coloration is often streaked or mottled, givingjadeite gemstones an interesting visual texture that carvers can use to createimaginative and intriguing effects.

The finest quality jadeite—almost transparent with a vibrant emerald-green color—is known as “Imperial jade.” The royal court of China once

had a standing order for all available material of thiskind, and it’s one of the world’s most expensive gems.Other highly valued jade varieties include “kingfisherjade,” with a green color that’s only slightly less vividthan Imperial; “apple jade,” which is an intense yellow-ish green; and “moss-in-snow jade,” which is translu-cent white with bright green veining, patches, or spots.The most outstanding examples of these are almostalways bought and sold in the Asian market.

The Maya and the Aztecs prized jadeite from CentralAmerica. They used it for medicinal purposes as well asfor jewelry, ornaments, and religious artifacts. Thename jade comes from the Spanish expression piedra deijada—literally “stone of the pain in the side.” EarlySpanish explorers named it after they saw natives hold-ing pieces of the stone to their sides to cure or relievevarious aches and pains.

It was in China—where the gem-carving traditionwas already thousands of years old—that jadeitereached its peak as an important artistic medium. Thefirst jadeite reached China from Burma (now known asMyanmar) in the late 1700s, and late eighteenth and

early nineteenth century carvers created masterpieces that are still unsur-passed in concept, design, and technical execution.

Jadeite is a favorite medium for lapidary artists around the world. This isespecially true in China, where jade carving is still a national art form. It’sa popular material for beads, cabochons, bangle bracelets, and small carv-ings. Because of its exceptional strength and toughness, it’s one of the fewgems that can be used to make hololiths—bracelets or rings carved entirelyfrom a single piece of stone, with no supporting metalwork or mounting.

Jadeite symbolizes prosperity, success, and good luck. It’s one of the top-selling gems in Asia, but its versatile beauty and cultural associations have alsoearned it an important place in the global gem and jewelry market.

SourcesGuatemalaMyanmar (Burma)RussiaUnited States

Hardness & ToughnessHardness 61/2 to 7 on Mohs scaleToughness Exceptional

StabilityEnvironmental Factor ReactionHeat Damaged by a jeweler’s torchLight StableChemicals Slightly affected by warm acids

47

Various colors of jadeite.

Lavender jadeite

Major source of finest qualitymaterial

48


Common

Common

Common

Heating Stable Unknown Undetectable


Dyeing(Referred to as“C jade”)

To add color(usually green orlavender) inwhite or light-colored material

Fair to good.May fade withtime

Detectable by atrained gemolo-gist or gemologi-cal laboratory*

Impregnationwith paraffinwax

Hides fracturesand improvespolish appear-ance

Fair. Heat willdestroy thetreatment

Detectable by atrained gemolo-gist or gemo-logical labora-tory*

Bleaching andimpregnationwith plastic-typepolymer resin.(A two-step pro-cess.) (Referredto as “B jade”)

Improves color;fills and hidesfractures andcavities;improves pol-ish appearance

Stable undernormal condi-tions. High heatcan damage ordestroy thepolymer

Sometimesdetectable by atrained gemolo-gist. Definiteproof usuallyrequiresadvanced testingby a gemologicallaboratory*

Producesbrown or red-dish color insome material

Jadeite and diamond brooch.


Ultrasonic cleaning Safe except for wax-impregnatedmaterial

Steam cleaning Safe except for wax-impregnatedmaterial

Warm, soapy water Safe


SyntheticsSynthetic jadeite has been producedon a limited basis. Identificationrequires advanced testing. (If there isany doubt, send the gem to a gemo-logical laboratory for verification.)

AlternativesAgateAmberBlack chalcedonyBloodstoneCarnelianChrysoprase chalcedonyMalachiteNephrite jadeOnyxRose QuartzShellTurquoise

49

Jadeite carving

Jade [Nephrite]

50

Nephrite jade has its cultural roots in the smoke-dimmed caves and huts thatsheltered prehistoric humans. In China, Europe, and elsewhere around theworld, Stone Age workers shaped this toughest of minerals into weapons,tools, ornaments, and ritual objects. Their carvings invoked the powers ofheaven and earth and mystic forces of life and death. The ancient relation-ship between this gemstone and humanity persisted into modern timesamong native societies in New Zealand and parts of North America. InChina it evolved into an artistic tradition that has flourished for more than3,000 years.

Nephrite is one of the two distinct minerals acceptedas jade in the international gem and jewelry industry.(Jadeite is the other.) It ranges from translucent toopaque and can be light to dark green, yellow, brown,black, gray, or white. Its colors tend to be more mutedthan jadeite’s, and they’re often mottled or streaked. Itsname comes from Latin words meaning “kidneystone”—a reference to the medicinal use of jadeite(with which nephrite was long confused) by NativeAmericans.

Generally inexpensive, extremely wearable, andavailable in all sizes, nephrite is often used in jewelryfor beads, cabochons, bangle-type bracelets, and carv-ings. The Chinese associate it with clarity of mind andpurity of spirit. Some of the ancient symbolic motifsstill used in modern jade carvings (both nephrite andjadeite) include:Bat—happinessButterfly—long lifeDragon—power, prosperity, and goodnessPeach—immortalityPi (flat circular disk with a hole in the center)—heaven

SourcesCanadaChina New ZealandRussiaTaiwanUnited States

Hardness & ToughnessHardness 6 to 61/2 on Mohs scaleToughness Exceptional (the toughest known

gem)


Heat Damaged by a jeweler’s torchLight StableChemicals Slightly affected by warm acids

51

Nephrite carving

52


Dyeing Occasional

Common

Heating Stable Unknown Undetectable



Ultrasonic cleaning Safe except for wax-impregnated material. Steam cleaning Safe except for wax-impregnated material. Warm, soapy water Safe

Produces orimproves color(usually green)in light-coloredmaterial

Variable,depending onthe type of dye


Impregnationwith paraffinwax

Hides fracturesand improvespolish appear-ance

Fair. High heatwill destroy thetreatment


Lightens color ofdark green mate-rial. Also dark-ens or “ages”white, yellow, orbrown material


AlternativesAgateAmberBlack chalcedonyBloodstoneCarnelianChrysoprase chalcedonyHematiteJadeite jadeMalachiteOnyxRose quartzShellTurquoise

53

KunziteKunzite/Spodumene

54

George Frederick Kunz (1856-1932) was a pioneer gemologist and longtimebuyer for Tiffany and Company. He was also a world-recognized experton—and avid promoter of—American gemstones. In 1902, he identified anew gem-quality variety of the mineral spodumene in San Diego County,California. The new gem was named kunzite in his honor.

This transparent stone’s light and delicate—but often bright—“rose” pinkto bluish purple “lilac” color has endeared it to gem lovers and connois-seurs, especially in the US and Japan. The most valued kunzite colors arethe more intense pinks and bluish purples, but the lighter pinks are the most

common. Kunzite is very popular with customers look-ing for gems in soft pastel colors.

The supply of fine-quality kunzite is limited, but var-ious faceted fancy shapes are usually available in sizesas large as 50 cts. The gem has poor toughness due tocleavage, and its attractive color can fade with exposureto bright light. Because of these factors, kunzite is agem that requires special care, but many consider theextra care worthwhile because of its beauty.

SourcesAfghanistanBrazilMadagascarUnited States

Hardness & ToughnessHardness 61/2 to 7 on Mohs scaleToughness Poor because of cleavage


Heat High heat can cause color loss; sudden temperaturechange can cause breaks

Light Bright light causes the color to fadeChemicals Very slowly attacked by concentrated hydrofluoric

acid


Irradiation Unknown Undetectable


Ultrasoniccleaning NeverSteam cleaning NeverWarm, soapy water Safe

ImitationsGlassSynthetic sapphireSynthetic spinel

AlternativesAmethystMorganiteRhodolite garnetRose quartzSapphireSpinelTopazTourmaline

55

Produceskunzite fromcolorless orlight-coloredspodumene

Color fades inbright light (asdoes untreatedmaterial)

Necklace designed by PalomaPicasso, featuring large kunzitewith diamonds and culturedpearls set in 18K gold

Lapis Lazuli

56

Lapis lazuli belongs to a small category of gems called “rocks” becauseit’s an aggregate of several different minerals. (A mineral is a natural inor-ganic material with a specific—and unique—chemical composition andcrystal structure). It’s often simply called “lapis” in the trade.

Lapis is typically opaque, and its colors are medium to dark greenish“navy” blue, pure “royal” blue, or violetish “midnight” blue. Depending onits source, it sometimes shows white calcite veining, which lowers its value,or golden-looking flecks of the mineral pyrite. The pyrite spangles nestledin the blue bodycolor—like golden stars in a summer sky—produce aunique visual appeal.

Lapis has been mined in Afghanistan for more than 6,000 years. It was trea-sured by the ancient civilizations of Mesopotamia, Egypt, China, Greece, andRome. Its Latin name literally means “blue stone.” Lapis was considered an

emblem of chastity and a cure for sadness. It was alsothought to offer protection from evil and ensure the helpof angels.

The supply of lapis is plentiful in today’s jewelry mar-ket. Large stones are readily available, and it’s a populargem material for beads, cabochons, tablets, and carvings.Afghan lapis has always been known for its fine qualityand color purity, while lapis mined in Chile often showsless-desirable white veining.

Lapis was dropped from the official US birthstone listin the 1950s, but for many years it was one of the gemsfor December. You might suggest it as an alternative forcustomers who were born in that month.

SourcesAfghanistan—Finest qualityChileRussia

Hardness & ToughnessHardness 5 to 6 on Mohs scaleToughness Fair


Heat High heat can induce an undesirable green color, orcause complete color loss

Light StableChemicals Decomposed slowly by hydrochloric acid; discolored

by cyanide solution


Dyeing Common

Common


Care and CleaningType of Cleaning AdvisabilityUltrasonic cleaning RiskySteam cleaning NeverWarm, soapy water Safe


AlternativesChalcedonySodalite

57

Improves colorand hides whiteveining

Fair. Somedyes fade or areaffected by sol-vents


Coating orimpregnationwith oil, paraf-fin, or plastic

Improves colorand polishappearance;also seals anydye

Fair. Treatment(especially oiland paraffin)can be dam-aged ordestroyed byheat and chem-icals

Detectable by atrained gemol-ogist or gemo-logical labora-tory*

Suite of high-quality lapis lazuli from Afghanistan

Malachite

58

Malachite is an opaque gem with a strong bluish green to green color. It typ-ically shows curved or circular banding (in varying shades of green) thatgives it a distinctive beauty. (A closely related gem material, azurmalachite,combines malachite green with the dark blue of the mineral azurite in attrac-tive bands and patterns.)

Malachite has a long history as a gem. One of its main components, andthe cause of its color, is copper. It was found along with that metal by earlycivilizations as they emerged from the Stone Age. The Egyptians used mala-chite for jewelry and other ornamental purposes as early as 4000 Bc. In theMiddle Ages (from about 500 to 1500 AD) people in Europe often hungmalachite on cradles to assure peaceful sleep for their children and protect

them from witchcraft. People wore pieces with eye-shaped markings as amulets to ward off the “evil eye.”

Modern jewelry uses for malachite include beads,cabochons, tablets, inlays, and carvings. Its high densitygives malachite jewelry such as bead necklaces a weightyfeeling that enhances customers’ sense of its value.Because malachite is relatively soft, has poor toughness,and can be attacked by many chemicals, it’s considered anextra-care gem. With proper handling, however, malachitecan provide years of pleasure for its wearer.

SourcesAustraliaRussiaUnited StatesZaire

Hardness & ToughnessHardness 31/2 to 4 on Mohs scaleToughness Poor

StabilityEnvironmental Factor ReactionHeat High heat can cause discoloration and damageLight StableChemicals Attacked by acids


Unknown





SyntheticsSynthetic malachite has been produced on a limited basis. Identification requires advanced testing. (If there is any doubt, send the gem to a gemological laboratory for verification.)

AlternativesAgate (dyed green)Jadeite jadeNephrite jadeTurquoise

59

Impregnationwith paraffin orepoxy resin

Intensifiescolor, improvespolish appear-ance, and hidessmall cracks

Fair. Treatmentcan be dam-aged ordestroyed byheat and chem-icals

Detectable by atrained gemol-ogist or gemo-logical labora-tory*

Suite of malachite

Malaya Garnet

60

Malaya (also spelled malaia) garnet is a relatively newmember of the garnet group. Specimens of it firstappeared in the 1960s, mixed in with parcels of rhodo-lite garnets from the Umba River Valley of East Africa.At first, buyers rejected the unfamiliar gem material, solocal miners and dealers gave it a Swahili name thatliterally translates “out of the family.”

Tests eventually proved malaya garnet to be a chem-ical mixture of two garnets: pyrope and spessartite. Thegem’s lively color—light to dark pinkish, reddish, oryellowish orange—conquered buyer resistance, andduring the 1980s it gained a small but strong market,particularly in the US.

Malaya is one of the more expensive garnets. It’susually available in various fancy shapes up to about 10cts. Along with the other garnets, it’s a US birthstone forJanuary. In Europe, malaya is known as umbalite, afterthe region that remains the gem’s only source.

SourcesKenyaTanzania



Heat Sudden temperature change cancause fracturing

Light StableChemicals Slightly attacked by hydrofluoric

acid




AlternativesAlmanditeCarnelianCitrineSapphireSpessartite garnetSpinelTopazTourmalineZircon

61

Color-change malaya garnets in fluorescent light

Color-change 8.51-ct.malaya garnet underincandescent light

Color-change 8.51-ct.malaya garnet underfluorescent light

Color-change malaya garnets in incandescent light

MoonstoneMoonstone/Orthoclase/Feldspar

62

According to Hindu mythology, moonstone is made ofsolidified moonbeams. Many other cultures also associ-ate this gem with moonlight, and it’s easy to see why. Itsinternal structure scatters the light that hits it and createsa phenomenon known as adularescence. The visualeffect is reminiscent of the full moon shining through aveil of high, thin clouds.

Legends say that moonstone brings good luck. Manybelieved that you could see the future if you held amoonstone in your mouth during a full moon.

Moonstone ranges from semitransparent to opaque.You’ll most often find it in cabochons and carvings, setin rings and pendants. It’s also popular in bead neck-laces and bracelets. It’s usually colorless, white, or lightbluish gray, with white or blue adularescence. Othercolors include light green, yellow, brown, and some-times gray to black. The market supply is normallysteady in sizes up to about 25 cts., with larger stonesavailable in limited quantities. Along with alexandriteand cultured pearl, moonstone is one of the US birth-stones for June.

SourcesIndiaMyanmar (Burma)Sri Lanka

Hardness & ToughnessHardness 6 to 61/2 on Mohs scaleToughness Poor because of cleavage

Faceted moonstone with blueadularescence


Heat High heat or sudden temperaturechange can cause breaks





AlternativesMilky chalcedony

63

Carved moonstone and diamond pendant

MorganiteMorganite/Beryl

64

In 1911, a transparent gem discovered on the African island of Madagascarwas hailed as an exciting new alternative to kunzite and pink tourmaline.The rose pink to lilac gem was named in honor of wealthy banker and gemconnoisseur John Pierpont Morgan. Morgan was an avid customer ofTiffany’s, and the jewelry store enthusiastically promoted the gem.

Eventually, Madagascar’s morganite deposits declined and Brazilbecame the gem’s top producer. Although the gem’s finest color is a deepmagenta, most morganites on the market are a pale pink. Many Brazilianmorganites emerge from the mines sporting an attractive peach (orange-

pink) hue that’s appealing to some buyers. But produc-ers usually heat treat gems of this hue to arrive at a pinkshade that’s preferred in the marketplace.

Morganite is a variety of beryl, which makes it a rel-ative of emerald and aquamarine. The gem’s beauty andlimited availability make it a favorite of collectors.

SourcesAfghanistan BrazilMadagascar US


StabilityEnvironmental Factor ReactionHeat Pinkish orange may fade to pink;

may fracture if liquid inclusionspresent

Light StableChemicals Resistant to all acids except

hydrofluoric

TreatmentsTreatment Purpose Stability Prevalence DetectionHeating Unknown Undetectable


Ultrasonic cleaning Risky if highly included (rare)Steam cleaning Risky if highly included (rare)Warm, soapy water Safe

AlternativesKunzitePink tourmalineRose quartzSapphireSpinelTopaz

65

Improves pinkcolor byremovingorange tint

Stable, exceptat temperaturesover 400°C

Onyx and SardonyxOnyx/Chalcedony and Sardonyx/Chalcedony

66

Onyx and sardonyx are both chalcedony varieties char-acterized by straight, parallel bands of different colors.In onyx, the bands are usually black and white. In sar-donyx, dark brown, brownish orange, or brownish redalternate with either white or black.

Since Greek and Roman times, both varieties haveprovided gem carvers with ideal materials for cameosand intaglios. The color banding allows the creation ofcarved designs that contrast dramatically with theirbackgrounds.

Inexpensive, plentiful, and available in large sizes,onyx and sardonyx are also traditionally popular forbeads, cabochons, and tablets. In Europe, sardonyxonce symbolized the humility of the saints and thevirtue of spiritual living.

Sardonyx is accepted as one of the US birthstones forAugust. (The other is peridot.)

SourcesBrazilMadagascarUnited StatesUruguay


StabilityEnvironmental factor Reaction

Heat Color may changeLight StableChemicals Attacked by hydrofluoric acid




AlternativesAgateCarnelianJadeite jadeNephrite jadeShell

67

Black and white onyx cameo set in gold andsurrounded by pearls

Sardonyx cameo

Opal

68

Opal is the world’s most popular phenomenal gem. Many cultures have cred-ited opal with supernatural origins and powers. Arabic legends say it falls fromthe heavens in flashes of lightning. The ancient Greeks believed opals gavetheir owners the gift of prophecy and guarded them from disease. Europeanshave long considered the gem a symbol of hope, purity, and truth.

Opal is one of the US birthstones for October (along with tourmaline).Some people think it’s unlucky for anyone born in another month to wearan opal. But that particular superstition comes from a novel written in the1800s (Anne of Geierstein by Sir Walter Scott) and not from ancient beliefor experience. In fact, throughout most of history, opal has been regarded

as the luckiest and most magical of all gems because itcan show all colors. Once, it was thought to have thepower to preserve the life and color of blond hair.

Although experts divide gem opals into many differentcategories, four of the main types are:• White opal—translucent to semitranslucent with

play-of-color against a white or light gray body-color

• Black opal—translucent to opaque with play-of-color against a black or other dark bodycolor

• Fire opal—transparent to translucent with brown,yellow, orange, or red bodycolor. This material—which often doesn’t show play-of-color—is alsoknown as “Mexican opal,” “gold opal,” or “sun opal”

• Boulder opal—translucent to opaque with play-of-color against a light to dark background. Host-rockfragments, or matrix, are part of the finished gem

The market supply of fine black opal is extremelylimited, but white and fire opals are generally avail-able in a wide range of sizes. You’ll usually see blackor white opals fashioned as cabochons and set in rings,pendants, pins, or earrings. Fire opals are used in thesame kinds of jewelry, but they’re often faceted. Allthree types occasionally appear as beads and carvings.

Pieces of white or black opal that are too thin to use alone often become part of opal doubletsor triplets. In these assembled stones, a sliver of opal is cemented—usually with black adhesivethat dramatizes the play-of-color—to a backing such as chalcedony, glass, or plastic. A doubletconsists of two pieces (the opal and the backing), while a triplet also has a protective top madeof rock crystal quartz or colorless glass.

Explaining Play-of-colorPlay-of-color occurs because opal is made up of sub-microscopic spheres stacked in a grid-likepattern—like layers of Ping-Pong balls in a box. This structure breaks up light into spectral colors.The colors you see depend on the sizes of the spheres. Those approximately 0.1 micron (one ten-millionth of a meter) in diameter produce violet. Spheres about 0.2 microns in size produce red.Those in between produce intermediate hues.

Common trade terms for play-of-color patterns include:• Pinfire or pinpoint—small, close-set patches of color• Harlequin or mosaic—broad, angular, close-set patches of color• Flame—sweeping reddish bands or streaks that shoot across the stone• Peacock—mainly blue and green

SourcesAustralia Black and white opalBrazil White opalMexico Fire opal

Hardness & ToughnessHardness 5 to 61/2 on Mohs scaleToughness Very poor to fair

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Blue opal pendant set in platinum with diamonds

Fire opal

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Heat High heat or sudden temperature change can causefracturing

Light Generally stable, but heat from intense light can causefracturing (known as “crazing”)

Chemicals Attacked by hydrofluoric acid and caustic alkalisWarn buyers that loss of moisture, and crazing, can result from storage in airtight containerssuch as safe deposit boxes.


Common

Common

Common


Impregnationwith oil, wax, orplastic

Improves play-of-color and preventsor disguises frac-turing. Black plas-tic also creates theappearance ofblack opal

Fair to poor foroil or wax; excel-lent for plastic

Oil and wax treat-ments are detectableby a trained gemol-ogist or gemologicallaboratory.Advanced laborato-ry testing is almost alwaysrequired for plastic*

Soaking in dye,silver nitrate, orsugar and acid(known as “sugartreatment”)

Creates orimproves play-of-color and simu-lates the appear-ance of blackopal

Poor to good Detectable by atrained gemolo-gist or gemologi-cal laboratory*

Smoke impregna-tion

Creates orimproves play-of-color and simu-lates the appear-ance of blackopal

Fair to poor.Treatment is shal-low, and abradesor chips awayeasily





SyntheticsAvailable in a variety of colors

AlternativesNo gem duplicates opal’s unique combination of color and phenomenon. Asalternatives, you might suggest stones with similar bodycolors, or those thatshow other special optical effects.Fire agateIris agate

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Pearl and Cultured Pearl

72

Perhaps the best-loved gems of all time, pearls—and their modern counter-parts, cultured pearls—occur in a wide variety of colors. The most familiarcolors are white and cream (light yellowish brown). Black, gray, and silverare also relatively common, but the palette of pearl colors extends to everyhue. The bodycolor is often modified by additional colors called overtones,which are typically pink (called rosé), green, purple, or blue. And somepearls show the iridescent phenomenon known as orient.

Pearls are treasures from the Earth’s streams, rivers, lakes, seas, andoceans, and they’ve always embodied the mystery, power, and life-sustainingnature of water. The spherical shape of some pearls also led many culturesto associate this gem with the moon. In ancient China, pearls were believedto guarantee protection from fire and fire-breathing dragons. In Europe, theysymbolized modesty, chastity, and purity.

Cultured pearls are popular for bead necklaces and bracelets, or mounted insolitaires, pairs, or clusters for use in earrings, rings, and pendants. Largerpearls with unusual shapes are favorites with creative jewelry designers.

Pearl—cultured or natural—is a US birthstone for June,together with alexandrite and moonstone.

Natural and Cultured PearlsNatural pearls are organic gems that form in the bodies ofcertain mollusks, usually around a microscopic irritant andalways without human help of any kind. They’re com-posed mostly of concentric layers of nacre, which is madeof the same basic material as mother-of-pearl—the insidelayer of certain shells. Natural pearls were once moreprevalent around the world—and prized by almost allcultures. They virtually disappeared from the mainstreamjewelry market in the twentieth century due to pollution,over-fishing, and economic factors. Now normally avail-able only through antique or estate dealers and auctions,fine natural pearls can command very high prices.

The growth of cultured pearls requires human inter-vention and care. The mollusks themselves are raisedspecifically for culturing. To begin the process, skilledtechnicians insert one or more nuclei (usually shell beadsor pieces of flesh from other mollusks) into each mollusk.These nuclei act as irritants and trigger the secretion ofnacre. Workers tend the mollusks until the cultured pearlsare harvested. This usually happens about 18 months, but

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occasionally up to 3 years, after nucleation. Besides human intervention,another big difference between natural and many cultured pearls is that the beadnucleus accounts for most of the volume and weight of the cultured product.

The first steps toward pearl culturing occurred hundreds of years ago inChina, and Japanese pioneers successfully produced whole cultured pearlsaround the beginning of the twentieth century. These became commerciallyimportant in the 1920s (about the same time natural pearl production beganto drop). From the 1930s through the 1980s, pearl culturing diversified andspread to various countries around the world.

A trained gemologist can often identify cultured pearls—particularly instrands, necklaces, or bracelets—with a reasonably high degree of certainty.Positive identification of natural pearls requires advanced laboratory testing. Ifthere is any doubt, send the gem to a gemological laboratory for verification.

FTC Guides on Pearls The US FTC Guides include several sections dealing with representations con-cerning natural, cultured, and imitation pearls. Some of the most importantpoints are: • It’s unfair or deceptive to use the term “pearl” alone or the term “natural”

(or anything similar) for cultured pearls or imitations• It’s unfair or deceptive to use terms such as “cultured,” “synthetic,” or

anything similar for imitation pearls• It’s unfair or deceptive to use the term “Oriental pearl” for anything

other than natural pearls from the Persian Gulf• It’s unfair or deceptive to use geographic terms like “South Sea” for

cultured pearls from other sources• It’s unfair or deceptive to use the term “pearl” or “cultured pearl” for

specimens of inferior appearance or quality

Cultured Pearl Types and Related Products• Akoya—the type of cultured pearl most familiar to many jewelry cus-

tomers. The typical size range is 6 mm to 8 mm, but you might see akoyacultured pearls as small as 2 mm or as large as 11 mm. Most have a whiteto cream bodycolor. Other natural colors include yellow, gray, and blue.Japan and China both produce saltwater akoya cultured pearls.

• South Sea—Australia, Indonesia, and the Philippines are leading sourcesof these saltwater cultured pearls. Myanmar (Burma) and Thailand arealso important producers. South Sea cultured pearls usually range fromabout 8 mm to 18 mm in size. The most common bodycolors are white,cream, and golden (dark brownish yellow), but you’ll see them in othercolors, too.

• Tahitian—Cultivated primarily around the islands of French Polynesia(the most familiar of which is Tahiti), these saltwater cultured pearlsusually range from white to black. Other colors include dark metallic

A pair of earrings with 2.22-ct. t.w. hot reddish pinkspinels, spessartite garnets, and cultured pearl drops

greens and purples. The usual size is about 8 mm to 17 mm, although larger pearls exist inlimited quantities.

• Freshwater—Pearls cultured in streams, rivers, and lakes. They’re produced in a wide rangeof sizes, shapes, and colors. China and the US are the leading sources.

• Keshi (Japanese for “poppyseed”)—Pearls that form (without being intentionally nucleated)in mollusks undergoing pearl cultivation.

• Blister pearls—Cultured or natural pearls that form over a solid core inside a freshwater orsaltwater mollusk’s shell. The side that faces the shell is flat and lacks nacre.

• Mabé—An assembled product consisting of a cultured blister pearl dome cemented to abacking made from mother-of-pearl shell. After harvesting, the nucleus is removed and thehollow interior is usually filled with a material such as epoxy resin.

Hardness & ToughnessHardness 21/2 to 4 on Mohs scale (very soft and easily scratched or abraded)Toughness Usually good, but variable due to aging, dehydration, and sometimes

excessive bleaching during initial processing


Heat High heat can burn cultured pearls or cause discol-oration, splitting, or cracking

Light Generally stable, but heat from intense light can causedehydration and nacre cracking

Chemicals Attacked by many chemicals and all acids; hair spray,perfume, cosmetics, and even acid perspiration candamage nacre

74

Harry Winston black cultured pearl and diamond cufflinks

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Bleaching Stable Undetectable,but assumed

Dyeing Common

Irradiation Stable Occasional



Ultrasonic cleaning NeverSteam cleaning NeverWarm, soapy water Safe for occasional, thorough clean-

ing (if strung, be sure the string iscompletely dry before wearing)

For routine care, advise customers to wipe cultured pearls with a very soft,clean cloth after each wearing.


AlternativesBlack chalcedonyCoralHematiteShell—mother-of-pearl

Routine for mosttypes of lightbodycolor cul-tured pearls; usu-ally considered astep in standardprocessing ratherthan a treatment

Lightens dark spots

Imparts orchanges body-color

Usually stable,but some colorsmay fade

Detectable by atrained gemologistor gemologicallaboratory*

Produces black,gray, or blue-graycolor in white orcream-coloredpearls

Sometimes detectableby a trained gemolo-gist, but often requiresadvanced testing by agemological laborato-ry*

Cultured black Tahitian pearls, 13-15.6-mm, 18K gold, with diamonds (31 pearls)

Peridot

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Peridot has always been associated with light. The Egyptians called it the“gem of the sun.” Some believed that it protected its owner from “terrors ofthe night,” especially when it was set in gold. Others strung the gem on don-key hair and tied it around the left arm to ward off evil spirits. Today,Arizona’s San Carlos Indian Reservation is the world’s most commerciallyimportant producer.

Peridot is usually transparent. It comes in an attractive range of colors,from brownish or yellowish green to greenish yellow. Customers will beattracted to the bright lime greens and more subdued olive greens of this

lovely gem.This gem is relatively inexpensive and plentiful, and

normally available in standard shapes and calibratedsizes up to about 5 cts. Larger stones are also fairly easyto find. Tumbled and faceted peridot is used for beadnecklaces and bracelets, often combined with gems incontrasting colors—amethyst, citrine, and pink tourma-line, to name a few.

The word peridot comes from the Arabic faridat, whichmeans “gem.” Most peridot formed deep inside the Earthand was brought to the surface by volcanoes. Some hasalso come to Earth in meteorites, but this extraterrestrialperidot is extremely rare, and you’re not likely to see it ina retail jewelry store. Mineralogists refer to the stone asolivine.

Peridot is one of the US birthstones for August (sar-donyx is the other).

SourcesMyanmar (Burma)PakistanUnited States

Hardness & ToughnessHardness 61/2 to 7 on Mohs scaleToughness Fair to good


Heat Rapid or uneven heat can causefracturing

Light StableChemicals Attacked easily by sulfuric acid,

and less easily by hydrochloricacid; can be attacked over a longperiod of time by acid perspiration


Ultrasonic cleaning RiskySteam cleaning NeverWarm, soapy water Safe

ImitationsGlassPlasticSynthetic sapphireSynthetic spinel

AlternativesChrysoberylDemantoid garnetEmeraldJadeite jadeSapphireTopazTourmalineTsavorite garnetZircon

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Topaz and peridot brooch with pearls set in yellow gold

PyropePyrope/Garnet

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Pyrope is a mineral that’s part of the garnet group. TheGreek word pyropos translates as “fiery-eyed,” and it’seasy to see how the gem got its name: The finestpyrope garnets have a glowing red color. Other pyropecolors range from medium to dark reddish orange topurplish red.

Pyrope was popular with the Greeks and Romans. Itwas prominent in jewelry of the Victorian era (1837-1901), but it’s now in short supply and seldom availablein sizes much larger than 2 cts. Collectors of antiquejewelry prize the elaborate Victorian jewelry set withmultitudes of small pyropes.

Like other garnets, pyrope is a US birthstone forJanuary. It’s occasionally called “Bohemian garnet,”after the region (now part of the Czech Republic) thatwas once an important source.

SourcesSouth AfricaUnited States



Heat Damaged by the heat of a jewel-er’s torch; sudden temperaturechange can cause fracturing


acid


Ultrasonic cleaning Usually safeSteam cleaning RiskyWarm, soapy water Safe

ImitationsGlassSynthetic ruby

AlternativesAlmandite garnetRhodolite garnetRubySpinelTopazTourmalineZircon

79

Pyrope (from Bohemia) bracelet

RhodoliteRhodolite/Garnet

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Rhodolite’s name is a modern composite of the Greekwords rhodon, “rose,” and lithos, “stone.” It’s a mem-ber of the garnet group, a mixture of almandite andpyrope. Technically, gemologists classify garnets by acombination of color and various tests, but to mostdealers and other gem professionals, any predominant-ly purple garnet is rhodolite. Rhodolite’s full colorrange includes light to dark purplish red through red-dish purple.

Rhodolite’s attractive color has made it one of themost valuable of the gems generally classified as “red”garnets. It’s also the best-selling garnet besides alman-dite, and enjoys a strong market supply and availabilityin a wide range of sizes. Like other garnets, rhodolite isa US birthstone for January.

SourcesSri LankaTanzaniaZimbabwe




Light StableChemicals Slowly attacked by hydrofluoric

acid



ImitationsGlassSynthetic ruby

AlternativesAlmandite garnetPyrope garnetRubySpinelTopazTourmalineZircon

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Pink rhodolite garnet, rose octagon cut, 2.34 ct., fromEast Africa

Fantasy cut rhodolite garnet (9mm x 21mm x 7mm)by Bart Curren set as pendant in 14K yellow gold

Rose QuartzRose Quartz/Quartz

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Rose quartz is a lovely quartz variety that typically ranges in color fromvery light to medium dark pink. Often, it has numerous internal fracturesthat give it a cloudy translucence and a visual texture that’s almost likethe veining in jadeite jade. Internal reflections sometimes give rosequartz specimens in the semitransparent range an intriguing “floatinglight” effect.

Sometimes, a multitude of tiny inclusions provides the stone with a stareffect. A cabochon cut combined with coating or mirror-like foil on the backenhances the star.

Rose quartz is generally inexpensive. You’ll see thebest color in the medium to large sizes: Small stoneswith good color can be harder to find. Its attractive colorand good durability make this gem a great choice forbead necklaces and bracelets.

Clean, close-to-transparent material might befaceted, while cabochon cuts are popular for stones setindividually in metal mountings. Carvings from largerpieces make beautiful pendants.

SourcesBrazilIndiaMadagascarSri Lanka



Heat High heat can cause change or lossof color; sudden temperaturechange can cause fracturing

Light Sometimes fades with prolongedexposure to bright light

Chemicals Soluble in hydrofluoric acid andammonium fluoride; very slightlysoluble in alkalis




AlternativesAgateKunziteSapphireSpinelStar sapphireTopazTourmaline

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Star rose quartz

RubyRuby/Corundum

84

Ruby has accumulated a host of legends over the centuries. In Sanskrit (theancient sacred language of India), one of the terms for ruby is ratnaraj,“King of Gems.” People in India believed that rubies enabled their ownersto live in peace with their enemies. In Burma (a ruby source since at least600 AD—now called Myanmar), warriors wore rubies to make themselvesinvincible in battle.

Many medieval Europeans wore rubies to guarantee health, wealth, wis-dom, and success in love. As the US birthstone for July, and the world’sbest-known and best-loved red gem, ruby still captivates the hearts andimaginations of gem professionals and consumers alike.

Large, fine-quality rubies are extremely rare andvaluable. But strong worldwide production and an arrayof treatments have increased availability and put rubieswithin the reach of most customers.

Common cutting styles for ruby include mixed-cutovals or antique cushions for transparent material, andcabochons or beads for translucent to opaque stones.Corundum has excellent toughness, and it’s harder thanany other natural gem except diamond. This makes itideal for rings as well as many other types of jewelry.

The name ruby comes from the Latin word ruber,which means “red.” The most expensive ruby color is adeep, pure, vivid red. Stones a little pinkish, purplish, ororangy red are also considered rubies, but gem and jew-elry professionals make careful distinctions betweenruby and pink, purple, or orange sapphire. (Ruby andsapphire are both corundum varieties.)

Generally, the difference depends on a combinationof hue, tone, and saturation, but market culture andgeography also make a difference. Gems that would beconsidered pink or purple sapphire in the US are oftenclassified and sold as rubies in some Asian countries.It’s important to keep such regional trade practice vari-ations in mind if you work in different markets, or withan international clientele.

15.97-ct. Burma ruby

SourcesAfghanistanKenyaMadagascarMyanmar (Burma)Sri Lanka Often lighter in tone than rubies

from Myanmar or ThailandTanzaniaThailand Mine production declined in the

1990s, but it’s still the worldcenter for treatment and whole-sale trade

Vietnam

Hardness & ToughnessHardness 9 on Mohs scaleToughness Usually excellent, but stones with certain treat-

ments or large fractures or inclusions can be lessdurable


Heat High heat can cause a change in color or clarity; it canalso damage or destroy fracture- and cavity-fillings

Light Generally stable, but heat from bright lights can causeoil to leak or dry out

Chemicals Can harm fillings and remove oil; soldering flux con-taining boron, and firecoat made with boric acid pow-der, will etch the surface of even untreated stones

85

Burmese ruby and diamond choker

Considered to produce finest qualityrubies

86


Heat

Occasional

Common


Improves colorand/or clarityappearance

Stable unlessthe stone isheated to veryhigh tempera-tures

Very common;experts esti-mate that up to95 percent ofstones undergosome sort ofheat treatment

May bedetectable by atrained gemolo-gist or gemologi-cal laboratory.*Can be unde-tectable, butassumed becauseof prevalence

Lattice diffusion(heating to veryhigh temperaturein the presence ofa coloring agent)

Cavity-fillingwith epoxyresin or glass

Creates red colorin corundum

Stable under nor-mal conditions,but the red colormight be removedin some stones ifthey’re repolishedor recut

Fairly common Detectable by atrained gemolo-gist or gemologi-cal laboratory*

Fracture-fillingwith oil or epoxyresin

Improves clarityappearance byhiding fractures.Colored oil orresin alsoimproves colorappearance

Fair. Heat andchemicals candamage ordestroy the fill-ing. Oil willprobably dry outor discolor intime


Improves clarityappearance byhiding cavities;adds weight if thecavities are large

Fair. Heat andchemicals candamage ordestroy the filling


1.02-ct. Burmese ruby


Ultrasonic cleaning Usually safe, but never for frac-ture- or cavity-filled stones

Steam cleaning Usually safe, but never for frac-ture- or cavity-filled stones

Warm, soapy water Safe, but avoid strong detergentsand vigorous scrubbing on oiledstones

ImitationsGlass

SyntheticsCzochralskiFlame fusionFloating zoneFluxHydrothermal

AlternativesAlmandite garnetPyrope garnetRhodolite garnetSpinelTopazTourmaline

87

Vietnamese rubies from Luc Yen and Quy Chau set injewelry (.33 - 1.94-ct)

Ruby and diamond braceletand necklace set

SapphireSapphire/Corundum

88

For centuries, sapphire has been associated with royalty and romance. The association wasreinforced in 1981, when Britain’s Prince Charles gave a blue sapphire engagement ring to LadyDiana Spencer. Until her death in 1997, Princess Di, as she was known, charmed and captivatedthe world. Her sapphire ring helped link modern events with history and fairy tales.

In ancient Greece and Rome, kings and queens were convinced that blue sapphires protectedtheir owners from envy and harm. During the Middle Ages, the clergy wore sapphires to sym-bolize Heaven, and ordinary folks thought the gem attracted heavenly blessings. In other timesand places, people instilled sapphires with the power to guard chastity, make peace betweenenemies, influence spirits, and reveal the secrets of oracles.

In folklore, history, art, and consumer awareness, sapphire has always been associated withthe color blue. Its name comes from the Greek word sappheiros, which probably referred tolapis lazuli. Most jewelry customers think all sapphires are blue, and when gem and jewelryprofessionals use the word “sapphire” alone, they normally mean “blue sapphire.”

In the trade, “blue sapphire” refers to stones ranging from very light to very dark greenish orvioletish blue, as well as those in various shades of pure blue. Large, top-quality stones are rare,but blue sapphires in other sizes and grades are almost always available.

Not all sapphires are blue, however. It’s a variety of the same species as ruby—corundum—and any corundum that doesn’t qualify as ruby isconsidered sapphire. Fancy sapphires, as they’re called,come in violet, green, yellow, orange, pink, purple, andintermediate hues. There are also parti-colored sapphiresthat show a combination of different colors. And somestones exhibit the phenomenon known as color change,most often going from blue in daylight or fluorescentlighting to purple under incandescent light. Sapphirescan even be gray, black, or brown.

Colorless sapphires were once popular diamond imi-tations, and in recent years they’ve staged a comebackas accent stones. Fancy sapphires are generally lessavailable than blue ones, and some colors are scarce,especially in very small or very large sizes. Still, fancysapphires create a rainbow of options for customerswho like the romance associated with this gem, but whoalso want something out of the ordinary.

Transparent sapphires of all colors are most oftenfaceted. Translucent to opaque material is usually cutinto cabochons or used for beads. Corundum is veryhard and tough, and can be used in any type or style ofjewelry, and worn by just about any customer. Sapphireis the US birthstone for September.

Special trade terms for fancy sapphires include:• amethystine or plum sapphire—purple

• golden sapphire—yellow or orangy yellow• padparadscha sapphire—pinkish orange to orange-pink with light to medium tone

and vivid saturation. The name comes from the Sinhalese term padmaragaya, or“lotus color.” (Sinhalese is the majority language of Sri Lanka.)

• white sapphire—colorless

SourcesAustralia Blue and fancyCambodia Blue and fancyChina Blue and fancyIndia/Pakistan (Kashmir)

Kenya Blue and fancyMadagascar Blue and fancyMyanmar (Burma)

Nigeria BluePakistan Fancy Rwanda FancySri Lanka Blue and fancyTanzania Blue and fancyThailand Blue and fancyUnited States Blue and fancy Vietnam Blue and fancy

Hardness & ToughnessHardness 9 on Mohs scaleToughness Usually excellent, but stones with large fractures or

inclusions, or some treatments, can be less durable


Heat High heat can cause change in color or clarity, and candamage or destroy fracture and cavity fillings

Light Generally stable, but irradiated yellow or orange stones fadequickly; heat from bright lights can cause oil to leak or dryout

Chemicals Can harm fillings and remove oil; soldering flux contain-ing boron, and firecoat made with boric acid powder, willetch the surface of even untreated stones

89

Padparadscha sapphire set in a ring with diamondsand blue sapphires

Famous historic source of fine blue sapphire, produc-tion is now very limited.

Blue and fancy

90


Heat

Irradiation Rare


Most commonlyimproves colorand/or clarityappearance

Stable unless thestone is heated tovery high tem-peratures

Very common forblue sapphires(experts estimatethat up to 95 per-cent of stonesundergo some sortof heat treatment);common for gold-en sapphires

May bedetectable by atrained gemolo-gist or gemologi-cal laboratory.*Can be unde-tectable, butassumed becauseof prevalence

Lattice diffusion(heating to veryhigh temperaturein the presence ofa coloring agent)

Creates almostany color incorundum

Stable under nor-mal conditions,but the colormight be removedin some stones ifthey’re repolishedor recut

Common foralmost all colors


Fracture fillingwith oil or epoxyresin

Improves clarityappearance byhiding fractures.Colored oil orresin alsoimproves colorappearance

Fair to good. Heatand chemicals candamage or destroythe filling. Oilwill probably dryout or discolor intime.

Rare for all colors

Detectable by atrained gemolo-gist or gemolog-ical laboratory*

Cavity fillingwith epoxyresin or glass

Improves clarityappearance byhiding cavities;adds weight ifthe cavities arelarge

Fair. Heat andchemicals candamage ordestroy the filling

Produces yellowor orange fromcolorless, lightyellow, and somevery light bluematerial


Rare for allcolors

Extremelypoor. Colorfades quickly(in minutes todays).

Detectable by“fade test.”(Place the stoneunder bright lightfor a couple ofdays)


Ultrasonic cleaning Usually safe, but never for fracture- or cavity-filledstones

Steam cleaning Usually safe, but never for fracture- or cavity-filledstones

Warm, soapy water Safe, but avoid strong detergents and vigorous scrub-bing on oiled stones

ImitationsGlassSynthetic spinel

SyntheticsCzochralskiFlame fusionFloating zoneFluxHydrothermal* If there is any doubt, send the gem to a gemological laboratory for verification.

AlternativesAlexandriteAmethystAquamarineChrysoberylCitrineKunziteMalaya garnetRhodolite garnetSpessartite garnetSpinelTanzaniteTopazTourmalineZircon

91

Sapphire and diamond necklace

Shell

92

Since prehistoric times, shell has been a by-product of the quest for food bycultures living around the Earth’s rivers, lakes, seas, and oceans. Long ago,humans began using attractive shells for jewelry. Because it’s durable andeasy to fashion, shell has remained popular as a gem material right up to thepresent. Its close association with water—especially the sea—gives it anaura of romance and magic similar to that of pearl and coral.

Ranging from translucent to opaque, shell comes inmany colors. The most common colors are white andvarious shades of gray, brown, yellow, orange, and pink.Some shell has bands or patterns of different colors.Other material shows the iridescent effect known asorient.

Its abundance, low cost and availability in largepieces make shell ideal for beads, cabochons, inlays,and carvings. Color-banded material is ideal for cameosbecause it allows the creation of designs that contrastdramatically with their backgrounds.

Some of the finest shell cameos appear in jewelryfrom the mid-1800s. During those years, QueenVictoria’s fondness for cameos created a fashion trendthat inspired skilled gem artists to produce masterpiecesof artistic and technical beauty.

Much of the shell used in today’s mainstream jewel-ry market—including imaginative designer pieces—comes from the mollusks that are also used for pearlculturing. Various species of shellfish provide materialfor the jewelry sold in tourist and resort locales.

The types of shell you’re most likely to see in a retailjewelry store include:

• Mother-of-pearl—the inside of the shell from a pearl-producing mol-lusk. The bodycolor is usually white, but it can also be brown or gray.Mother-of-pearl’s rich luster and frequent display of orient come closeto duplicating the appearance of pearl (but only on one side of thematerial).

• Abalone shell—mother-of-pearl that’s usually from the molluskknown to scientists as haliotis. It typically has dark gray or brownbodycolor and striking orient. Abalone from the waters aroundAustralia and New Zealand is often called Paua shell. Its bright blueand green orient gives it the look of a peacock’s tail feathers.

• Conch shell—obtained from the giant queen conch. Its color usuallyranges from pale to fairly bright pink or orange. The color is often lay-ered or banded with white, and some shells have a pattern described asflame-like. The queen conch also produces a material known as conchpearl. It has an attractive porcelain-like sheen, but it lacks the pearlycoating of a true pearl. The sunrise-pink color and flame patterns offine specimens make them treasures for gem connoisseurs, especiallyin Europe, the Middle East, and Asia.

• Helmet shell—the type most often used for cameos. It’s generally lay-ered in two colors: white and brown, orwhite and orange.

• Ammonite—the fossilized shellsof squid-like animals that flour-ished about 65 million yearsago. (Their closest livingrelative is the chamberednautilus.) The shells havea coiled shape, and speci-mens with iridescenceare the ones used injewelry, sometimes asassembled stones withquartz tops.

93

Gem-inlaid shells are used in producing such jewelryitems as cufflinks, earrings and pins

94

SourcesAustralia Abalone, mother-of-pearlCanada AmmoniteItaly A center for shell carvingMadagascar HelmetNew Zealand AbaloneUnited States Abalone, conch, mother-of-pearl, ammoniteWest Indies Conch, helmet

Hardness & ToughnessHardness 31/2 on Mohs scaleToughness Fair


Heat Blackens in the flame of a jeweler’s torchLight Generally stable, but conch shell and some dyed mate-

rial gradually fades in sunlightChemicals Easily attacked by acids


Dyeing Common


Produces a vari-ety of colors

Fair. Dyes mayfade


Black and white shell cameo set in gold




AlternativesAgateCarnelianCoralCultured pearlFire agateJadeite jadeMoonstoneNephrite jadeOnyxRose quartzSardonyx

95

Cameos fashioned from mother of pearl shell

Smoky QuartzSmoky Quartz/Quartz

96

Smoky quartz is one of the most common and inexpensive transparent gemson the market. Its color varies from light to dark brown, and some stones areso dark they’re almost black. Smoky quartz is a traditional gem in theScottish Highlands. There, it’s also known as cairngorm, after theCairngorm Mountains of Scotland, an old but now depleted source. Verydark smoky quartz—often called morion—was popular in the sombermourning jewelry of the late Victorian period (1861-1901).

You’ll seldom see smoky quartz in sizes under a carat, but larger stonesare always available in most standard shapes and sizes. Smoky quartz has

good durability, so it’s suitable for any type of jewelry.Its color makes it a good choice as a gemstone accentfor warm yellow and orange wardrobe colors.

Because of its color, many consumers (and some pro-fessionals) confuse smoky quartz with topaz, but topazis a different gem species.

SourcesBrazilSwitzerlandUnited States



Heat High heat can cause change or loss of color;sudden temperature change can cause fracturing

Light StableChemicals Soluble in hydrofluoric acid and ammonium

fluoride; very slightly soluble in alkalis


Irradiation Excellent Common

Heat Excellent Occasional



AlternativesChalcedonyCitrineMoonstoneTopazTourmalineZircon

97

Producessmoky quartzfrom rock crys-tal (colorlessquartz)

Lightens thecolor of verydark material

Undetectable(duplicates pro-cesses that occurnaturally)

Undetectable(duplicates pro-cesses thatcolor naturalmaterial)

Faceted and rough smoky quartz

8500 ct. smoky quartz

SpessartiteSpessartite/Garnet

98

Customers who think all garnets are red will be surprised and delighted withspessartite (also known as spessartine). Some gems of this garnet species area bright and lively orange. Others range from medium-light to dark yellow-ish or reddish orange.

Market supply is sometimes limited, but rounds and fancy shapes are nor-mally available in sizes up to 10 cts. You can usually also find larger stoneswith a little searching. Prices for spessartite—especially stones from moreremote locations and those with a bright orange color—are generally a littlehigher than those for red garnets like almandite and pyrope.

The gem’s name comes from Spessart, a district inthe state of Bavaria, Germany, that was once an impor-tant source. Customers born in January are among thosemost likely to be interested in spessartite, because itoffers a birthstone color that’s a little different.

SourcesBrazilMadagascarMyanmar (Burma)NamibiaSri LankaUnited States




Light StableChemicals Very slowly attacked by hydroflu-

oric acid


Ultrasonic cleaning Usually safe, but risky for stoneswith large or numerous inclusionsor fractures


ImitationsGlassSynthetic sapphire

AlternativesAmberCarnelianCitrineFire opalMalaya garnetSapphireSpinelTopazTourmaline

99

Spinel

100

Spinel is a good candidate for the title of “History’s Most Under-Appreciated Gem.” Some ancient mines that supplied gems for royal courtsfrom Rome to China produced spinels, but they were usually confused withbetter-known stones like ruby and sapphire.

Some of the world’s most illustrious “rubies” are actually spinels. One ofthese is the Black Prince’s Ruby, a polished but unfaceted red spinel thatweighs about 170 cts. It appears in historical records dating back to the1300s, and it’s a central stone in the British Imperial State Crown.

Modern technology hasn’t helped spinel’s confused identity, either—atleast, as far as the general public is concerned. This is largely due to thewidespread use of synthetic spinel as an imitation for many other gems.Most customers don’t even know there’s a natural version of the stone.

Limited availability also contributes to spinel’s lack of public recogni-tion. Gem-quality material is typically transparent and faceted, but it’s hardto find in sizes larger than 5 cts.

Spinel’s color range includes violet, blue, orange, red, pink, and purple.Blue spinels are often grayish and subdued, but the best are a deep richcolor. The reds can rival fine ruby. And the vivid orange to orange-red stones

merit their trade name—flame spinel. Some spinelsshow color-change, usually turning from grayish blue indaylight or fluorescent light to purple under incandes-cent light.

In addition to its attractive colors, spinel is a hard,tough stone that’s suitable for daily wear in any type ofjewelry. It will always be popular with customers wholike beautiful and unusual gems.

SourcesCambodiaMyanmar (Burma)

Sri LankaTanzaniaThailand


Known for fine-quality pink andred spinels

StabilityEnvironmental factor Reaction

Heat High heat may cause the color to fadeLight StableChemicals Stable



ImitationsGlassSynthetic rubySynthetic sapphire

SyntheticsFlame fusionFlux

AlternativesAlmandite garnetAmethystAquamarineFire opalKunziteMalaya garnetMorganitePyrope garnetRhodolite garnetRubySapphireSpessartite garnetTanzaniteTopazTourmaline

101

Red spinel from Myanmar (Burma)

Blue spinel

Star RubyStar Ruby/Corundum

102

According to Eastern folklore, star rubies ward off eviland bring good luck to their owners. But the marketsupply of these auspicious gems is generally very lim-ited. Fine stones are rare prizes eagerly sought by col-lectors and connoisseurs.

Star rubies vary from semitransparent to opaque andfrom light to dark red or purple-red. They display aphenomenon called asterism. It’s caused by tiny nee-dle-like inclusions that reflect and scatter light withinthe stone. Star ruby’s star usually has six rays, and itrequires skilled cabochon cutting to bring it out.

The finest star rubies are almost transparent, with astrong deep color that rivals non-phenomenal rubies.They show a sharp, complete star that glides smoothlyback and forth as you rock the stone gently.

Star rubies display their optical charms best whenthey appear as center stones in elegant ballerina-stylering settings, surrounded by flashing diamondbaguettes.

The typical size range for star rubies is 1 ct. to 10cts., but much larger stones exist. One of the largestfine-quality star rubies on public display is theSmithsonian Institution’s 137-ct. Rosser Reeves Ruby.

Along with ruby, star ruby is considered a US birth-stone for July.

SourcesIndiaKenyaMyanmar (Burma)Sri LankaTanzaniaThailand

Hardness & ToughnessHardness 9 on Mohs scaleToughness Excellent except in stones with repeated twinning or

large fractures


Heat High heat can burn oil and changethe stone’s color or the quality ofthe star effect

Light Generally stable, but heat frombright lights can cause oil to leakor dry out

Chemicals Can remove oil; soldering fluxcontaining boron, and firecoatmade with boric acid powder, willetch the surface of the stone

103

Star ruby from Tanzania

104


Occasional Undetectable

Occasional

Rare


Heating fol-lowed by slowcooling

Stable unlessthe stone isheated to veryhigh tempera-tures and thencooled rapidly

Creates orimproves thestar effect

Oiling or dyeing Hides cracksand improvesclarity andcolor appear-ance

Fair. Can bedamaged ordestroyed byhigh heat andsolvents. Oilwill probablydry out or dis-color in time.


Lattice diffusion Creates the stareffect

Stable undernormal condi-tions, but thestar effect canbe damaged ordestroyed if thestone is repol-ished or recut



Ultrasonic Cleaning Safe except for oiled stones andthose with fractures

Steam Cleaning Safe except for oiled stones andthose with fractures

Warm, soapy water Safe, but avoid strong detergentsand vigorous scrubbing on oiledstones

ImitationsGlass or other inexpensive material engraved with a star on the backside ofthe stone, or backed with metallic foil engraved with a star design.

SyntheticsFlame fusion

AlternativesStar almanditeStar moonstoneStar rose quartzStar sapphireStar spinel

105

Star SapphireStar Sapphire/Corundum

106

A cabochon-cut star sapphire characteristically shows a six-rayed star,caused by needle-like “silk” inclusions that reflect and scatter light. Starsapphires range from semitransparent to opaque. They come in many ofthe same colors as non-phenomenal sapphires, but supplies of most colorsare limited: Green star sapphires are rare, and yellow or orange ones arevery rare.

Black star sapphire, which ranges from translucent to opaque, is oftenvery dark brown, green, or blue, rather than true black. It’s the most avail-able and least expensive natural star stone, and it’s especially popular for

men’s jewelry.Modern heat treatments that remove inclusions from

rough material have made fine-quality star sapphiresrare. Marketed gems typically range from 1 ct. to 10 cts.in size, but you can sometimes find larger stones aswell. The American Museum of Natural History’s col-lection includes one of the world’s largest and mostspectacular blue star sapphires—the 153-ct. Star ofIndia.

Some traditions say that star sapphire is a stone ofdestiny, and that its star acts as a guiding light and pro-tects its wearer against evil. To medieval Christians, thethree intersecting bands that form the star representedthe spiritual virtues of Faith, Hope, and Charity. Today,star sapphire provides a phenomenal September birth-stone alternative.

SourcesAustraliaKenyaMyanmar (Burma)Sri LankaTanzaniaThailand

Hardness & ToughnessHardness 9 on Mohs scaleToughness Excellent except in stones with repeated twinning or

large fractures


Heat High heat can burn oil andchange the stone’s color or thequality of the star effect

Light Generally stable, but heat frombright lights can cause oil to leakor dry out

Chemicals Can remove oil; soldering fluxcontaining boron, and firecoatmade with boric acid powder,will etch the surface of the stone

107

108


Occasional Undetectable

Occasional

Rare



Ultrasonic cleaning Safe except for oiled stones and those with fracturesSteam cleaning Safe except for oiled stones and those with fracturesWarm, soapy water Safe, but avoid strong detergents and vigorous scrub-

bing on oiled stones

Heating followedby slow cooling

Creates orimproves thestar effect

Stable unlessthe stone isheated to veryhigh tempera-tures and thencooled rapidly

Oiling or dyeing Hides cracksand improvesclarity andcolor appear-ance

Fair. Can bedamaged orremoved byhigh heat andsolvents. Oilwill probablydry out or dis-color in time.


Lattice diffusion Creates the stareffect

Stable undernormal condi-tions, but thestar effect canbe damaged ordestroyed if thestone is repol-ished or recut


ImitationsGlass or other inexpensive material engraved with a star on the backside ofthe stone, or backed with metallic foil engraved with a star design.

SyntheticsFlame fusion

AlternativesStar moonstoneStar rose quartzStar rubyStar spinel

109

A 3,965-ct. sapphire from an area of Sri Lanka that isknown to produce star sapphires of over 500 cts.

TanzaniteTanzanite

110

Tanzanite is relatively new to the colored stone galaxy. This transparent blue gem first turned upin 1962, scattered on the Earth’s surface in northern Tanzania, a country in eastern Africa.Scientists identified it as a variety of the mineral zoisite. About five years later, a prospector dis-covered a large deposit of it in the same area, and serious mining began.

Tiffany & Company recognized its potential as an international seller and made a deal tobecome its main distributor. Tiffany named the gem after the country it came from, and pro-moted it with a big publicity campaign in 1968. Almost overnight, tanzanite was popular withleading jewelry designers and other gem professionals, as well as with customers who had aneye for beautiful and unusual gems.

Tanzanite’s public recognition and popularity have grown steadily. But there have been widefluctuations in the gem’s supply and price level, due mostly to Tanzania’s volatile political, social,and economic conditions. That country remains the gem’s only source, so the outlook for long-termavailability is also doubtful. (You can keep up with its market variability by reading industry publi-cations, attending trade shows, and talking to suppliers.)

Tanzanites are heat-treated to produce colors that include light to dark violetish blue andbluish purple, as well as pure blue. Rich, deep hues are valued most, but you’ll usually see theseonly in stones weighing 5 cts. or more. This is mainly because of decisions made during the cut-ting process. Tanzanite typically shows strong pleochroism, which means it displays different

colors from different directions. It usually looks vio-letish blue from some directions, purplish from others.

Predominately blue tanzanite is generally worthmore per carat, but because of the way tanzanite crys-tals grow, a cutter can usually get a bigger stone by ori-enting the gem to show the purple color. With smallrough, size is normally the main consideration. Whilethe trade considers the pure blue stones to be “top”grade, some customers actually prefer the lighter andmore purplish colors. This means you can offer themwhat they like best at an affordable price.

Tanzanite is special-care gem for two reasons: sensi-tivity to thermal shock and the potential for cleavage.Sometimes the temperature change between the hotlights of the display case and the chilly glass countertopin an air-conditioned showroom can be enough to devel-op cleavages in tanzanite.

Because of its susceptibility to cleavage, tanzaniteshouldn’t be handled carelessly. If you’re helping youngor active customers select tanzanite jewelry, try sug-gesting pieces that won’t be too exposed to accidentalbumps—pendants and earrings are good choices. Foreveryday wear, it’s best to select jewelry that’s designedto protect the stone.

SourcesTanzania

Hardness & ToughnessHardness 6 to 7 on Mohs scaleToughness Fair to poor, due to cleavage and sensitivity to thermal shock


Heat Sudden temperature change can cause crackingLight StableChemicals Attacked by hydrochloric and hydrofluoric acid


Heat Stable Routine



ImitationsGlassSynthetic sapphireSynthetic spinelSynthetic spinel triplet

AlternativesAmethystIoliteSapphireSpinel

111

Produces tanzan-ite color in trans-parent brownishmaterial

Undetectable, butassumed becauseof prevalence

Tiger’s-EyeTiger’s-Eye/Quartz

112

Tiger’s-eye is one of the top-selling phenomenal gems. Varying fromtranslucent to opaque, it comes in warm earth tones that include brown,brownish yellow, and reddish brown. Its main distinguishing characteristicis its “eye,” called chatoyancy.

Tiger’s-eye’s chatoyancy is different from the chatoyancy in cat’s-eyechrysoberyl. For one thing, it usually has a wavy appearance, rather than astraight, sharp look. Also, tiger’s-eye can be cut in many ways, even flat, whilecat’s-eye has to be fashioned as a cabochon to bring out the phenomenon.Explanation for these differences lies in their different “eye” causes: In tiger’s-eye, reflections of light from the fibrous structure of the gem itself create theeye, while in cat’s-eye, the eye comes from inclusions rather than structure.

Tiger’s-eye is inexpensive and available in most standard sizes. It’s a popu-lar material for cabochons (usually with flat backs), beads, tablets, cameos, and

intaglios. Good toughness makes tiger’s-eye a great gemfor everyday wear, and it’s a frequent choice for men’sjewelry

Other chatoyant quartz gem varieties are scarcer andusually more expensive. These include:• Hawk’s-eye or falcon’s eye—grayish blue material

with chatoyancy like tiger’s-eye• Zebra tiger’s-eye—tiger’s-eye with grayish or blue

streaks• Cat’s-eye quartz—brownish yellow, brownish green

to greenish yellow. Shows a true cat’s-eye effect. (Itmust be cut as a cabochon to show the eye.)

SourcesIndiaSouth AfricaSri Lanka



Heat Sudden temperature change can cause fracturingLight StableChemicals Soluble in hydrofluoric acid and ammonium fluoride;

very slightly soluble in alkalis


Excellent Common

Heat Excellent Common Undetectable

Dyeing Common





AlternativesCat’s-eye chrysoberylCat’s-eye tourmaline

113

Bleaching(sometimes fol-lowed by plas-tic coating)

Lightens thecolor. Plasticcoating seals thefibrous structureand prevents con-tamination withdirt and foreignmatter

Undetectable,but light brown-ish yellow coloris a strong indi-cation of treat-ment

Produces areddish browncolor

Adds variouscolor

Usually good.Some dyes maybe affected bysolvents, or fadewith prolongedexposure to brightlight.


114

Topaz

Most authorities agree that the name topaz comes from Topazios, the oldGreek name for an island in the Red Sea, now called Zabargad. (The islandnever produced topaz, but it was once a source of peridot, which was con-fused with topaz before the development of modern mineralogy.) Somescholars trace the origin back to Sanskrit (an ancient language of India) andthe word topas or tapaz, meaning “fire.”

The ancient Greeks believed that topaz gave them strength. In Europeduring the Renaissance (the period from the 1300s to the 1600s) peoplethought that topaz could break magic spells and dispel anger. For centuries,many people in India have believed that topaz worn above the heart assureslong life, beauty, and intelligence.

Most consumers are under the impression that topazis an easy gem to recognize. But what they might thinkof as topaz could actually be the more common citrineand smoky quartz. This confusion shows when you’redisplaying topaz jewelry and your customer says some-thing like “I didn’t realize topaz was so expensive” or“Isn’t topaz brown?” You will need to clear up thesemisunderstandings before you go further in your pre-sentation.

Topaz actually has an exceptionally wide color rangethat, besides brown, includes various tones and satura-tions of blue, green, yellow, orange, red, pink, and pur-ple. Colorless topaz is another option. The color vari-eties are often identified simply by hue—blue topaz,pink topaz, and so forth—but there are also a couple ofspecial trade names:• Imperial topaz—medium reddish orange to orange-

red. This is one of the most expensive colors. • Sherry topaz—yellowish brown or brownish yellow

to orange. This term comes from the color of sherrywine. (Stones in this color range are often calledprecious topaz to help distinguish them from theless expensive citrine and smoky quartz.)

115

Strong output from sources around the world andtreatments that expand the range of usable gems guaranteea steady supply of topaz. However, market availabilityvaries according to color. Blue topaz is abundant, andthere’s usually plenty of sherry topaz, but the supply ofimperial, red, purple, and pink tends to be limited.

Most colors are available in standard faceted shapes,but the sizes differ from color to color. Blue usuallyranges from 1 ct. to 25 cts., while other colors normallyrun from 1 ct. to 10 cts. You might also find some largerstones, especially in sherry or blue.

Generally, red is the most valuable topaz color, butmarket prices and preferences vary from country tocountry. Imperial topaz brings highest prices in Japanand Germany. Japanese buyers also favor pink topaz. Thebiggest market for blue topaz is in the US, where it pro-vides a gem alternative that’s lower in cost and moreintense in color than aquamarine.

The biggest faceted gem (by weight) ever recorded is a topaz in thecollection of the Smithsonian Institution. Named the “American Golden,”it’s a light yellow stone that weighs 22,982 cts. (4.60 kg or 10.14 lb.) andmeasures 17.3 cm ˘ 14.9 cm ˘ 9.2 cm (6.7 in. ˘ 5.8 in. ˘ 3.6 in.).

Today, topaz is one of the US birthstones for November. (The other iscitrine.) Topaz is a hard stone, but it can develop cleavage. Keep this inmind when you’re showing jewelry, and advise customers to be a little extracareful when wearing this gem.

SourcesAustraliaBrazilMadagascarMexicoMyanmar (Burma)NamibiaNigeriaPakistanSri LankaUnited States

Topaz carving from Idar-Oberstein

116

Hardness & ToughnessHardness 8 on Mohs scaleToughness Poor due to cleavage


Heat High heat can alter color; sudden temperature changecan cause breaks

Light Generally stable, but some brown stones fadeChemicals Affected very slightly


Heat Stable Common

Stable


Changes someyellow, orange,or brown mate-rial to pink

Undetectable,but usuallyassumedbecause ofprevalence

Irradiation fol-lowed by heat

Produces vari-ous shades ofblue from color-less material

Routine(almost allmedium to darkblue topaz isproduced bytreatment)

Usually unde-tectable, butassumedbecause ofprevalence.Occasionallydetectable by agemologicallaboratory.Caution: Mayvery rarely bedangerouslyradioactive*

9.73-ct. topaz from Brazil

Bue topaz




AlternativesAquamarineCitrineHessonite garnetKunziteMalaya garnetMorganiteSapphireSmoky quartzSpessartite garnetSpinelTourmalineZircon

117

Topaz crystal

Tortoise Shell

118

Tortoise shell is an organic gem material from the shellof the hawksbill sea turtle. It ranges from semitranspar-ent to translucent, with a mottled appearance that’s usu-ally yellow and brown, but occasionally black andwhite. For centuries, artisans used tortoise shell to makejewelry and other items, including combs and decora-tive furniture inlays. It was also a popular material foreyeglass frames and guitar picks.

Hawksbill turtles are an endangered species. Sincethe 1970s, they’ve been protected under the UNConvention on International Trade in EndangeredSpecies of Fauna and Flora (CITES). Most of the morethan 100 countries that are parties to the convention alsohave supporting laws or regulations that ban commercein tortoise shell.

US federal law prohibits the import or sale of itemsmade from hawksbill shell, unless they can be proven tobe at least 100 years old. Pieces that aren’t that old, butwere made and privately owned before 1974, can belegally purchased from individuals or estates, but onlyfor a collection, and not for resale.

Hardness & ToughnessHardness 21/2 on Mohs scaleToughness Fair


Heat Softens at the temperature of boiling water; high heatdarkens, then burns the material

Light May darken with ageChemicals Attacked by nitric acid


Occasional



Ultrasonic cleaning NeverSteam cleaning NeverWarm, soapy water Safe, but hard-bristle brushes can

leave scratches

ImitationsPlastic

AlternativesAgateAmberSardonyxShell

119

Lamination(pieces are soft-ened and joinedtogether withheat and pres-sure)

Made thickermaterial forcarving

Variable,depending onhow well thelayers werejoined


Tortoise shell box

Tourmaline

120

People have probably used tourmaline as a gem for centuries, but until thedevelopment of modern mineralogy, they identified it as some other stone(ruby, sapphire, emerald, and so forth) based on its color. Portuguese explorers,for example, discovered deposits of green tourmaline in Brazil in the mid-1500s, but they thought it was emerald.

The confusion about the stone’s identity is even reflected in its name,which comes from toramalli, which means “mixed gems” in Sinhalese (alanguage of Sri Lanka).

In the late 1800s, tourmaline became known as an American gem throughthe efforts of Tiffany gemologist George F. Kunz. He wrote about the tour-maline deposits of Maine and California, and praised the stones they pro-

duced. In spite of its American roots, tourmaline’sbiggest market was in China, where the imperial courtprized tourmaline as a material for small carvings andutilitarian objects like snuff bottles.

The supply of tourmaline began to expand during thefirst half of the twentieth century, when Brazil yieldedsome large deposits. Then, beginning in the 1950s,additional finds appeared in countries around the world.

Tourmalines come in a wide variety of exciting col-ors. In fact, tourmaline has one of the widest colorranges of any gem species. It occurs in various shadesof almost every hue, and there are a number of tradenames for its color varieties:• Rubellite—pink, red, purplish red, orangy red, or

brownish red. (Some in the trade argue that pinktourmaline shouldn’t be called rubellite.)

• Indicolite—dark violetish blue, blue, and greenishblue.

• Paraíba tourmaline—intense violetish blue, greenishblue, or blue from the state of Paraíba, Brazil. (Thisvariety was discovered in 1988.)

• Chrome tourmaline—intense green. (Much of this iscolored by vanadium, the same element that colorsmany Brazilian and African emeralds.)

• Parti-colored tourmaline—tourmaline with more than one color. One ofthe most common combinations is green and pink, but many others arepossible.

• Watermelon tourmaline— pink in the center and green around the out-side. Crystals of this material typically have a pink core surrounded bygreen, and they’re cut in slices.Some tourmalines also show chatoyancy. Cat’s-eye tourmalines are most

often green, blue, or pink, with an eye that’s softer and more diffused thanthe eye in fine cat’s-eye chrysoberyl. This is because, in tourmaline, theeffect is caused by thin tube-like inclusions that occur naturally during thegem’s growth. The inclusions are larger than the inclusions in cat’s-eyechrysoberyl, so the chatoyancy isn’t as sharp. Like other cat’s-eyes, thesestones have to be cut as cabochons to bring out the effect.

SourcesAfghanistanBrazil Major sourceKenyaMadagascarMozambiqueMyanmar (Burma)NamibiaPakistanRussiaUnited States

Hardness & ToughnessHardness 7 to 71/2 on Mohs scaleToughness Fair


Heat High heat can alter color; suddentemperature change can cause frac-turing

Light Generally stableChemicals None

121

Bi-colored emerald cut tourmaline set with diamonds

122


Heat Stable Common Undetectable

Irradiation Undetectable

Acid Stable Occasional Undetectable

Occasional




Lightens verydark green orblue-greenstones; convertsbrownish purplestones to “rose”pink; producesbright greenishblue to yellowishgreen stones fromgrayish Paraíbamaterial

Produces deeppink, red, or pur-ple from verylight pink, green,blue, or colorlessmaterial; convertssome light yellowor green materialto a darker yellowor orange; turnssome greenstones into redand green parti-colored

Common forpink, red, andpurple.Occasional foryellow, orange,and parti-color.

Fair to good.Color may fadeunder high heator very prolongedexposure to brightlight.

Improves theappearance ofcat’s-eye stones

Fair. Heat andsolvents can dam-age or destroy thesealant.

Prevents dirtfrom gettinginto the tubesthat cause thecat’s-eye effect

Sealing tubes incat’s-eye materialwith plastic orepoxy resin


ImitationsGlassSynthetic rubySynthetic sapphireSynthetic spinel

AlternativesAlmandite garnetAmberAmethystAquamarineCat’s-eye chrysoberylChrysoberylCitrineEmeraldFire opalKunziteMalaya garnetMorganitePeridotPyrope garnetRhodolite garnetRubySapphireSmoky quartzSpessartite garnetSpinelTanzaniteTopazTsavorite garnetZircon

123

Freshwater cultured pearl torsade with decorativeclasp featuring tourmaline slices.

TsavoriteTsavorite/Grossularite/Garnet

124

Kenya’s Tsavo National Park is home to some of the largest remaining pop-ulations of Africa’s legendary animals, including lions, elephants, giraffes,and zebras. In the early 1970s this wildlife wonderland also gave the worldan exciting new gem. Scientists identified the stone as a transparent greenvariety of the garnet species known as grossularite. In 1974, Tiffany &Company introduced it to the US market as tsavorite. (It’s often calledtsavolite in Europe.)

Only a few sources of tsavorite have been discovered, so supplies of itare limited. Because of its often delightfully bright color, it has become one

of the most sought-after and expensive garnets. Itscolor ranges from light to dark—but always intense—yellowish green or green. You’re likely to see tsavoriteonly in fairly small sizes—from about 50 pts. to 3 cts.The largest faceted tsavorite on record weighs a littleunder 24 cts.

Because tsavorite is part of the garnet family, it’s aUS birthstone for January. Its intense green color andthe fact that it’s generally untreated make it an exotic,high-quality alternative to emerald. It’s an intriguingtwentieth century gem that can add zest to any cus-tomer’s jewelry collection.

SourcesKenyaTanzania

Hardness & ToughnessHardness 7 to 7 1/2 on Mohs scaleToughness Fair to good




acid


Ultrasonic cleaning Usually safe, but risky if the stonecontains liquid inclusions


ImitationsGlassSynthetic emeraldSynthetic spinel

AlternativesDemantoid garnetEmeraldPeridotTourmaline

125

Tsavorite garnet and diamonds in gold ring

Turquoise

126

Turquoise is one of the world’s most ancient gems. Archaeological excava-tions revealed that Egyptian royalty wore turquoise jewelry as early as 5500BC, and Chinese artisans were carving it more than 3,000 years ago.Turquoise is the national gem of Tibet, and has long been considered a stonethat guarantees health, good fortune, and protection from evil.

Turquoise was a ceremonial gem and a medium of exchange for NativeAmerican tribes in the southwestern US. They also used it in their jewelryand amulets. The Apaches believed that turquoise attached to a bow orfirearm increased a hunter’s or warrior’s accuracy.

The gem’s name comes from the French expressionpierre tourques, or “Turkish stone.” The name, whichoriginated in the thirteenth century, reflects the fact thatthe material probably first arrived in Europe fromTurkish sources.

Turquoise can be translucent to opaque, with a colorthat usually ranges from light to medium blue or green-ish blue. It’s often mottled, and sometimes has darksplotches. It might also have veins of matrix runningthrough it (matrix is its surrounding rock). In the mate-rial known as spiderweb turquoise, fine seams of matrixform attractive web-like patterns. The most valuableturquoise is an even medium blue, with no matrix, andthe ability to take a good polish.

Turquoise is plentiful and available in a wide rangeof sizes. It’s used for beads, cabochons, carvings, andinlays. Although well known to consumers, its popular-ity in the mainstream jewelry industry comes and goes.The biggest and most permanent market is in theAmerican Southwest. It’s also popular elsewhere,among customers who are captivated by that region’smystery and romance, as well as by the blue of its skies.Turquoise is one of the December birthstones. (Zirconis the other option for that month.)

SourcesChinaIran Historical source of the finest material (known as

Persian turquoise): No longer commercially importantUnited States

Hardness & ToughnessHardness 5 to 6 on Mohs scaleToughness Generally fair to good


Heat High heat can cause discolorationand surface damage

Light StableChemicals Dissolves slowly in hydrochloric

acid; can be discolored by chemi-cals, cosmetics, and even skin oilsor perspiration

127

128


Common

Common

Common

Occasional


Impregnationwith wax orplastic (some-times with dyeadded)

Improves thecolor and lusterof pale materi-al; plastic alsoimproves dura-bility

Excellent tofair. Plastic isstable undernormal condi-tions, but waxmay graduallydeteriorate anddiscolor.

Detectable by atrained gemolo-gist or a gemo-logical labora-tory*

Painting matrixwith black shoepolish or simi-lar colorants

Makes thematrix a desir-able color

Fair. Solventscan damage ordestroy thetreatment.


Backing withepoxy resin

Adds thickness,strength, andweight topieces other-wise too thin tocut

Good undernormal condi-tions. Heat orsolvents candamage ordestroy theepoxy backing.

Detectable by atrained gemolo-gist or a gemo-logical labora-tory if the stoneis unmounted*

Filling cavitieswith metal-loaded epoxy

Hides cavitiesand imitatespyrite inclu-sions

Fair. Heat orsolvents candamage ordestroy the fill-ings, and theymay eventuallyseparate evenunder normalconditions.




ImitationsGlassPlastic“Reconstructed turquoise,” usually made of various powdered minerals—not turquoise—dyed and bonded with plastic, epoxy resin, or similar sub-stances.

SyntheticsSynthetic turquoise was produced on a limited basis inthe 1980s, but it was never widely available on the mar-ket. A trained gemologist or gemological laboratory canidentify the material. (If there is any doubt, send the gemto a gemological laboratory for verification.)

AlternativesAgateChrysocolla chalcedonyJadeite jadeLapis lazuliMalachiteNephrite jade

129

Turquoise and diamond pin in the form of a closedflower

Zircon

130

Many people have heard of zircon but never seen it. Mostly, this is becauseof colorless zircon’s wide use as a diamond simulant in the early 1900s. Itwas long ago replaced in that role by more convincing look-alikes, but itsname still means “imitation” to many people. That’s unfortunate—or, rather,it creates an opportunity for creative customer education—because zircon isa beautiful colored stone with its own fair share of folklore and charm.

Zircon is one of the US birthstones for December (the alternate isturquoise). In the Middle Ages, this gem was thought to induce sound sleep,drive away evil spirits, and promote riches, honor, and wisdom. Manyscholars think the stone’s name comes from the Arabic word zarkun, mean-ing “cinnabar” or “vermilion.” Others believe the source is the Persian wordzargun, or “gold colored.” Considering zircon’s color range, either deriva-tion seems possible.

The most common color for the zircons on today’smarket is a distinctive greenish blue that’s often called“zircon blue.” Others include green, yellow, orange,red, brown, and even purple. The colors are often lightand muted, but the finest stones have strong, rich colors.

Zircon is one of the few colored stones that mightshow visible dispersion. When you’re showing thisgem, look for flashes of rainbow-colored fire and pointthem out to customers.

The supply of zircon is generally limited, and typicalsizes depend on color. Blue or green stones normallyrange from 1 ct. to 10 cts., yellows and oranges up toaround 5 cts., while reds and purples are usually small-er. Most colors are available in various fancy shapes,but colorless and blue stones are often fashioned in thestyle known as the zircon cut—a round brilliant witheight extra facets around the culet.

Zircon has medium hardness, and the heat treatmentthat produces many of its colors might also make zirconbrittle. For this reason, it’s safest to recommend zirconin earrings or pendants, or in protected ring settings.This will keep the gem from becoming scratched andabraded and make it less vulnerable to fracturing.

SourcesAustraliaCambodiaChinaMyanmar (Burma)Sri Lanka ThailandVietnam

Hardness & ToughnessHardness 6 to 71/2 on Mohs scaleToughness Fair to good; heat-treated stones can be brittle and

might be easily abraded


Heat High heat can alter colorLight Generally stable; some heat-treated stones revert to

their original color (light brown)Chemicals None


Heat

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Produces color-less, blue, yel-low, orange, orred from brownmaterial

Generally sta-ble, but somestones revertwhen exposedto light

Routine. Almostall blue or color-less zircons aretreated.

Undetectable,but usuallyassumed due toprevalence

Various colors of zircon

132



ImitationsCubic zirconiaGlassSynthetic sapphireSynthetic spinel

AlternativesAlmandite garnetAmethystAquamarineChrysoberylCitrineDemantoid garnet (also shows strong dispersion)Fire opalHessonite garnetKunziteMalaya garnetPeridotPyrope garnetRhodolite garnetRubySapphireSpessartite garnetSpinelTopazTourmaline

Green zircon, Sri Lanka, 5.68 cts.

Blue zircon

Brown zircon

ACKNOWLEDGMENTSThe Gemological Institute of America gratefully acknowledges the following people and organizations fortheir assistance in providing some of the gems, jewelry, and photography used in this assignment:

23rd St. Shoppe, 43 (top), 77 (bottom), 114, 122, 123 (bottom)A. Ruppenthal KG, 83 (middle)Carol Ackerman, 111 (right)Chris Almquist, 121 (top)Assael International, 75Bear Essentials, 33 (bottom)Jonte Berlon, 124Matt Bezak, 117 (bottom)Gordon Bleck, 40, 100, 101 (top left), 102, 107 (bottom), 108, 132 (middle)Gary Bowersox, 13 (bottom), 27 (middle), 54, 55 (top), 57, 132 (bottom left)Buccellati, 74 (bottom left)Alan Caplan, 35 (right)Carolyn Tyler Designs, 2 (bottom)Christie’s Images Inc., 34, 46, 88Don Clary, 27 (top), 81 (bottom)Cody Opal, 70Coffin & Trout Jewelers, 125 (top)Colgem Ltd., 98Creative Jewelers, 2 (top)Crescent Jewelers, 55 (middle), 115 (bottom)Crystal Reflections, 23Bart Curren, 11 (middle and bottom), 81 (top)Brian Davenport, 87 (top), 91 (left)Anil B. Dholakia, Adris Oriental Gem and Art Corp., 43 (bottom)Dona Dirlam, 81 (top)Ali Farook, 104Emmanuel Fritsch, 3 (bottom)Fu Gemstone Import, 106Mary Murphy Hammid, 5 (top and bottom)Herring & J.T. McManus, 12Herrling-Schmuck, 78Debbie Hiss-Odell, 39, 90Hixon Collection, 47 (top)David Humphrey, 19 (bottom), 71 (left), 130JCK Magazine, 132 (top)J. Grahl Design, 10 (bottom), 11 (top), 37 (top), 72, 73 (bottom), 74 (top), 85, 120, 123 (top)Jim Shaylor Jewelers, 36 (left)Neil Lane, 16Ledge Studio, 97 (top)Glenn Lehrer, 97 (top)Dave LeRose, 86, 116 (bottom)Andy Lucas, 61 (top)Martin Chung Gemstones and Fine Jewelry Co., 13 (top), 56, 61 (top), 84 (bottom)Mayer & Watt, 5 (top and bottom), 80Elise Misiorowski, 3 (middle)Ginger Moro, 8, 96, 129 (right)Bernd Munsteiner, 121 (bottom)Natural History Museum of Los Angeles County, 89 (top)Pala International, 99, 125 (middle)Peter Secrest Collection, 17 (top)Smithsonian, 109 (right)Kent Raible, 73 (top)Ramsey Gem Imports, 64Rigoberto Jewelry Designs, 6, 7, 20, 21, 38, 39Serengeti West, 125 (bottom)C.Y. Sheng, 26, 27 (bottom)Silverhorn, 4Michael Stubin, 17 (bottom right)Suzanne Tennenbaum, 29 (top)Tiffany & Co., 13 (middle), 55 (bottom), 110Van Cleef & Arpels, 88Harry Winston, 74 (right)Elizabeth Ziegler, 10 (top)Benjamin Zucker, 17 (bottom left)

133

134

Sylvia Bissonette, 10 (bottom), 11 (top), 37 (top), 72, 73 (bottom), 74 (top), 85, 120, 123 (top)

Nicholas DelRe, 43 (bottom), 93 (top), 95 (bottom)

Tino Hammid, 2 (bottom), 4, 5 (top, middle, bottom), 6, 7, 10 (top), 16, 17 (bottom left), 19 (middle), 22, 27(second), 29 (top), 32, 37 (bottom), 38, 39, 43 (top), 47 (top), 55 (middle), 60, 61 (all), 65 (top), 68, 73 (top), 77(bottom), 80, 81 (top), 84 (top), 90, 100, 101 (top), 107 (top), 114, 115 (bottom), 121 (top), 122, 123 (bottom),124, 130, 131

Mike Havstad, 29 (bottom), 31 (top), 41, 47 (bottom), 51 (bottom), 59 (top), 66, 69 (top), 71 (right), 97 (bottomright), 101 (bottom), 116 (left)

John Koivula, 9 (bottom left and right), 33

Shane McClure, 35 (top), 64, 87 (bottom), 103

Tim Nighswander, 111 (top)

Jeffrey Scovil, 17 (top), 65 (bottom)

Michael Stubin, 17 (bottom right)

Maha Tannous, 33 (bottom), 42 (top)

Harold & Erica Van Pelt, 36 (right)

Fred Ward, 109 (left)

Robert Weldon, 2 (top), 3 (top, middle, bottom), 6 (top), 8 (top), 11 (middle and bottom), 12, 13 (top and bottom),19 (top and bottom), 23, 25, 26, 27 (top, bottom two), 28, 33 (middle), 36 (left) 40, 42 (bottom), 44, 54, 55 (top),56, 57, 62 (all), 63 (bottom), 71 (left), 74 (bottom left and right), 75, 81 (bottom), 83 (top and bottom), 84(bottom), 86, 87 (top), 89 (top), 90, 91 (left), 95 (top), 96, 97 (bottom left), 98, 99, 101 (middle), 102, 104, 106,107 (bottom), 108, 111 (bottom), 115 (top), 116 (right), 117 (bottom), 121 (bottom), 125 (middle and bottom),127, 128, 129 (right), 132 (top, middle, bottom)

PHOTO CREDITS

Documents

GIA's Colored Stone Essential's Reference Guide