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PEARLS
Jodie Diegel, GG, MBA
Graduate GemologistGemological Institute of America
PEARLS The Product
Types of Pearls Farming Cultured Pearls Making Bead Nuclei Nucleating the Oyster Farming Cultured Pearls Raising Production Stock Harvesting Cultures Pearls Processing Cultured Pearls Judging Pearl Value Factors
The Product Pearls are classified by
gemologists as cultured stones. They are not “inorganic” as most
stones are but “organic” They come from an animal or plant Other examples includes amber,
coral, ivory and jet
The Product Natural Pearls Cultured Pearls Saltwater Freshwater
Fewer than 20 species of the 8,000 mollusks produce pearls
The Product The world’s main
pearling grounds were depleted in the 18th century due to constant demand
By the beginning of the twentieth century most of the world’s pearl-producing mollusks were in immediate danger of extinction
The Product Pearls are made of NACRE
A natural substance produced by mollusks that also costs the inside of the animal’s shell (also called “mother of pearl”)
Nacre is made up mostly of calcium carbonate in the form of the mineral aragonite and held together by crystal layers called conchiolin
The Product Natural Pearls
Parasitic Invasion Mollusk forms a sac around the intruder and secretes
nacre from the mantle tissue (the layer of tissue that surrounds the body of the mollusk and lines the shell)
Cultured Pearls Human assistance w/bead or tissue nucleation
Nacre secreted around bead or mantle tissue Beads for saltwater oysters Tissue for freshwater
Fewer than 20 species of the 8,000 mollusks produce pearls (also “keshi” pearls)
The Product Pinctada fucata “Akoya”
Mostly found in Japan White/cream/yellow “Mikimoto” Pearls usually 2-11mm in size,
majority 6-7 mm Usually spherical preferred Approximately 2000 pearl farms in
Japan
The Product Pinctada maxima “South Sea”
Australia, Philippines, Indonesia Largest size yellow/silver Often 9-20 mm with the majority
about 13 mm
The Product Pinctada margaritifera “Tahitian”
French Polynesia (Tahiti) Black/silver Spherical generally range in size from
8-13 mm Often black hue but different tones
Farming Cultured Pearls Natural supply has depleted over
centuries Need highly trained technician and
mantle tissue
Making Bead Nuclei Beads often come from freshwater
shells from US Need minimum sizes to keep
mussels American Pearl Company
Nucleating the Oyster 2 types of nucleation
Bead Tissue
When nucleated: Slow metabolism Careful opening (Tahitian and South
Sea can be re-nucleated) Add Tissue and/or bead nucleus Freshwater usually tissue alone (no
bead)
Farming Cultured Pearls Pearls Farms
Small family farms Large commercial/sophisticated
operations Problems/Challenges
Pollution Severe weather (drought/flooding) Red Tide
Raising Production Stock Collecting from wild
More labor intensive Divers
Hatcheries More controlled but size limited
“Spat” collection Especially Tahitians
Harvesting Cultured Pearls Every 2-3 months mollusks
cleaned Harvesting:
8-24 months Akoya 2 years Tahitian/South Sea 2-6 years Freshwater
Harvesting Cultured Pearls Only South Sea and Tahitian are
kept alive and can be nucleated again Subsequent pearls are LARGER!
Freshwater may be once more Akoya can have up to 5 beads Freshwater can hold up to 50 pieces
of mantle tissue
Processing Cultured Pearls Bleaching Dyes Sorting
Size, shape, luster, surface quality, matching ability
Drilling Full (necklaces) Half (earrings, posts)
Judging Pearl Quality There are 7 features that directly
affect a cultured pearl’s beauty and value
Collectively called “VALUE FACTORS” Understanding these will give you the
product knowledge to help recognize the beauty and rarity of all pearl types
Judging Pearl Quality 1. SIZE A pearl’s ultimate size can depend
on many variables Size and health of the mollusk Size of the nucleus Amount of time in the water adding
layers of nacre Larger pearls usually more valuable
Judging Pearl Quality 2. SHAPE While round is perhaps the most
familiar shape, pearls come in many different forms.
Spherical, Symmetrical, Ovals, buttons, drops, baroque
Judging Pearl Quality 3. COLOR A pearl’s color is made up of Hue-the color’s first impression Tone-its lightness or darkness Saturation-its strength or intensity GIA recognizes 19 pearl hues
Judging Pearl Quality 4. LUSTER “The true magic of a pearl
lies in its luster” and how it reflects light Luster is the most important of all of the
value factors to the beauty of a pearl. 4 categories:
Excellent-reflections bright, sharp, distinct Good-bright reflections but not sharp Fair-weak and hazy Poor-dim, no reflections
Judging Pearl Quality 5. SURFACE QUALITY Cultured pearls are organic so it isn’t
surprising when they show surface characteristics.
Abrasions, bump, chips, cracks, gaps, pit, scratches, spots or wrinkles
Categories: Clean Lightly blemished Moderately blemished Heavily blemished
Judging Pearl Quality 6. NACRE QUALITY Nacre is the very essence of the pearl
itself A pearl’s appearance helps determine its
quality and it has a LOT to do with whether the nacre is thick or thin (thin=“blinking”)
Classifications: Acceptable Nucleus Visible Chalky Appearance
Judging Pearl Quality 7. MATCHING The matching value factor is
relative (only applies to strands, or jewelry with more than one pearl)
Classifications: Excellent Good Fair
CONCLUSION Pearls have been and are forever
fashionable, and were revered in Asia since approx. 4000BC
With the advent of culturing, new and exciting pearls have become available in the last century
More affordable due to great influx of freshwater pearls
CONCLUSION Pearls invoke
words such as
Purity Devotion Love Rarity Romance Elegance
CONCLUSION QUESTIONS?