Diamond Identification Vilnius Helsinki Aug 2008

7/28/2019 Diamond Identification Vilnius Helsinki Aug 2008

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Diamond Identification

Dr.James

ShigleyGemologicalInstituteofAmerica

Carlsbad,California

GIAResearch


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PresentationOutline

Identification:NaturalColoredDiamonds

Synthetic

DiamondsClarityTreatedDiamondsColorTreatedDiamonds

Summary


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NaturalColored

Diamonds

22.28caratChameleon Diamond


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Diamond

CharacterizationGemology:

Internal

features

(inclusions,

color

distribution,

luminescence)Ultravioletfluorescence

Absorptionspectrapattern

Strain

pattern

and

intensityPhotomicrographsandfluorescenceimages

Spectroscopy:

Midinfraredabsorption

Ultravioletvisiblenearinfraredabsorption

Photoluminescence

Ramanidentificationofsignificantinclusions

1

1.5

2

2.5

4500 4000 3500 3000 2500 2000 1500 1000


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Diamond

Type

Classification

TypeI

TypeIaaggregatednitrogenatoms

(IaA,IaB,IaAB subcategories)

TypeIbdispersed

nitrogen

atoms

TypeII

TypeIIafew

if

any

impurities

TypeIIbdispersedboronatoms


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Absorption

Spectroscopy

.5

1

1.5

2

2.5

3

3.5

4000 3500 3000 2500 2000 1500 1000

-.05

0

.05

.1

.15

.2

.25

400 500 600 700 800 900

Infraredspectra

Visiblespectra


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Luminescence

Spectroscopy

0

50000

100000

150000

200000

550 600 650 700 750 800 850

Luminescencespectra


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Photography

Faceup

Externalfeatures Inclusions

Strain Fluorescence


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Data

Collection

for

each

Diamond

1.2

1.4

1.6

1.8

2

2.2

300 400 500 600 700 800

0

50000

100000

150000

200000

250000

500 600 700 800 900

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

10000 8000 6000 4000 2000

Weight/Cut: 1.00ct/cushion

Color: FANbr

PK

Clarity: SI2

LWUV: mediumBlue

SWUV: weakBlue

Spectra: nosharplines

Strain: weakcrosshatched

Inclusions:none

DiamondView

Crosspolarized20x

Infraredabsorption UVVisibleNIRabsorption

Photoluminescence

488 laser

514 laser

633 laser

830 laser

midIRnearIR


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Groups

of

Natural

Diamonds

TypeIa

Cape

TypeIb

TypeIIb

Orange

Pink

Chameleon

Green

DtoZcolors


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Diamond

Color

versus

Market

Value

Market

Value

Color

Colorless Faintcolor Fancycolor


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Colored

Diamond

Publications


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HPHT

Grown

Synthetic

Diamonds

As-Grown

TType Ib

Type IIb

Type Ib + IIb

Type IIa

Treated

Annealing

Irradiation

+

Annealing

Irradiation


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HPHTGrown

Synthetic

Diamonds

Diamondgrowthoveraperiodofseveraldaysathighpressuresandtemperatures(HPHT)fromametalsolvent


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HPHTGrown

Synthetic

Diamonds

Welbournetal.,Gems&Gemology,Fall1996

Cuboctahedral crystalmorphology


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HPHTGrown

Synthetic

Diamonds

Welbourn

et

al.,

Gems

&

Gemology,

Fall

1996

Internalarrangementofgrowthsectors


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HPHTGrown

Synthetic

Diamonds

Internalarrangementofgrowthsectors

Welbournet

al.,

Gems

&

Gemology,

Fall

1996


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HPHTGrown

Synthetic

Diamonds

Colorzoningpatterns


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HPHTGrown

Synthetic

Diamonds

Internalgrainingpatterns


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HPHTGrown

Synthetic

Diamonds

Inclusions

of

flux

metals


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HPHTGrown

Synthetic

Diamonds

Ultravioletfluorescencecolorsandpatterns


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Synthetic

Diamond

Chart

Gems&

Gemology

(Winter

2004)


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CVD

Grown

Synthetic

Diamonds

Diamondgrowthatlowpressuresandhightemperatures


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Asgrown

colorlessandnearcolorless

Asgrown

darkbrown

As

grownorange pink

HPHTtreated

colorlessandnearcolorless

HPHTtreatedyellow

Apollo

CVD

Synthetic

Diamonds


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Apollo

CVD

Synthetic

Diamonds

DTCDiamondView images

OrangyRed

UV

Fluorescence Blue

UV

Phosphorescence


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ApolloCVD

Synthetic

Diamonds

70x 40xSurfacecavitiesandfractures


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Apollo

CVD

Synthetic

Diamonds

Mosaicbirefringencepatternsseeninpolarizedlight


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ApolloCVD

Synthetic

Diamonds

100x 90xGirdlesurfaceandlaserinscriptionmarks


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Apollo

CVD

Synthetic

DiamondsVisibleAbsorption

0

5

10

15

20

300 400 500 600 700

Wavelength (nm)

Ab

sorptionCoefficient(cm-1)

620 640 660 680 700 720420 440 460 480 500

637

666 685 712495

503

413419

425

~520

~

270

637


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TypeIa (rarelyIIa) TypeIIaColorless(tolightyellow) Colorless(brown)Cape absorptionspectrum Nospectrumpattern

BlueUV

fluorescence Orange

UV

fluorescence

Weaktostrongfluorescence WeakfluorescenceComplexinternalgrowth BandedinternalgrowthOccasionalinclusions Inclusions rare

Octahedralor

irregular

shape Tabular

shape

TypeIa UVopaque TypeIIa UVtransparent

Natural CVDSynthetic

Colorless Diamonds


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Clarity

Enhanced

Diamonds

Alaserisusedtoburnanarrowopenchannelfromthesurfacetoa

mineralinclusion

Acidsareintroducedthroughthischanneltodissolveorbleachthe

inclusion


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Clarity

Enhanced

Diamonds

Morerecently,heatfromthelaserisusedtoextendapreexistingfracturetothe

surface,and

acids

are

introducedthroughthisfracturetodissolveor

bleachthemineral

inclusion


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Clarity

Enhanced

Diamonds

Patternsofinternallaserdamage


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Clarity

Enhanced

Diamonds

Opensurfacereachingfracturesarefilledwithahighrefractiveindexglasstohidetheirvisibility

Before After


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Clarity

Enhanced

DiamondsBefore After


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Clarity

Enhanced

Diamonds

Flasheffect colors

seen

with

magnificationagainstbrightordarkbackgrounds


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Clarity

Enhanced

Diamonds


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Structure

Defects

in

Diamonds

Anidealdiamondthatisfreeofatomiclevel

defectsis

colorless

Allnaturaldiamondscontainvariousdefects

(impurity

atoms,

missing

or

displaced

carbon

atoms)

Someofthesedefectscanselectivelyabsorbvisible

light,

and

can

impart

various

colors

in

diamond

0.95carat


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Radiationproduces

vacanciesthat

selectively

absorbredlightandintroducebluecoloration

Whenannealed,

avacancy

combineswithnitrogentoformvariousdefectswhich

impart

yellow

or

yellowgreencoloration

Diamonds

Treated

by

Radiation


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Irradiated

Colored

Diamonds

Electronradiationproducesathinlayerofcolorbeneathfacetsurfaces

Reflectionsofthisthinlayercanbeseenasadistinctive

colorpattern

near

the

culet


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Irradiated

Colored

Diamonds

Acolorconcentrationatthe

culetdue

to

exposure

to

electronradiation


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1.4

1.6

1.8

2

2.2

2.4

2.6

400 450 500 550 600 650 700 750

Wavelength (nm)

Abs

orbance

ND1

GR2

GR3

GR1

Irradiated

Colored

Diamonds

Visiblespectrum

withabsorption

featuresdue

toradiationexposure


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Spectroscopy

of

Diamond

Liquidnitrogencryogenicunit


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1

1.5

2

2.5

3

350 400 450 500 550 600 650 700

Wavelength (nm)

Absorbance

H3H4

N3

594

Irradiated+Heated Colored

Diamonds

Visiblespectrumwith

absorption

featuresduetoheating


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Irradiated

(+

Heated)

Diamonds


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HPHT

Treated

Diamonds

Annealingatveryhighpressuresandtemperaturesforashorttimetochangediamondcolor


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HPHTTreatedDiamonds

~2200C

Lightbrown(typeIIa) Nearcolorless(H)


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HPHT

Treated

Diamonds

Surfacedamageduetoheatingathightemperaturesandpressures


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HPHT

Treated

Diamonds

TreatmentofbothTypeIandTypeIIdiamonds


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HPHTTreatedDiamonds

Internal

graphitization


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HPHT

Annealing

ExperimentsBeforetreatment

Aftertreatment

HPHT A li f Di d


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HPHTAnnealingofDiamond

1

1.5

2

2.5

3

350 400 450 500 550 600 650 700

Wavelength (nm)

Absorbance

AfterHPHT

BeforeTreatment

H3

N3


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HPHTIdentificationChallenges


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Diamonds

Treated

by

Multi

Processes

Major effects of radiation with or

without annealing:

Introduce vacancies

Produce H3 and H4 defects

Produce N-V centers

Major effects of HPHT annealing:

Remove plastic deformation-

related brown color

Release H-compensated

boron

Produce defects like H2 and

H3

Generate isolated nitrogen


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Multi

Process

Treated

Diamonds

Graphitizationalongfractures Etchedareasonsurface

Bothfeaturesareevidenceofhightemperatureannealing

M l i P T d Di d


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Aconcentrationofpink orangecolorattheculetisevidencethatadiamondhasbeenirradiatedandannealed

Type IIa

MultiProcessTreatedDiamonds

Type Ia


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1.5

2

2.5

3

3.5

4

450 500 550 600 650 700

Wavelength (nm)

Absorbance

N3

425

H3

594

637

(N-V)-

575

(N-V)0

H4

VisibleSpectrum(TypeIa)Multi

Process

Treated

Diamonds


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0.01 to 1.57 ct

Serenity

Surface

Coated

Diamonds

S it S f C t d Di d


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Iridescentthincoloredcoatingsonfacetsurfaces

SerenitySurfaceCoatedDiamonds

Serenity Surface Coated Diamonds


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SerenitySurfaceCoatedDiamonds

Visualevidenceofasurfacecoating


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New

Publication

from

GIA

Republicationof

articles

andotherinformationontreateddiamondsand

their

identification

that

haveappearedinGems&Gemologyoverthepast50years

Diamond Research Summary


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DiamondResearch Summary

Bycharacterizing

the

propertiesofdiamonds,wearecreatingadatabaseof

information

that

can

be

used

todeveloppracticalmeansfortheiridentificationtosupportthejewelrytrade

20.17carats

Gem Identification Summary


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GemIdentification Summary

In

addition

to

standard

testing

equipment,

today

gem

identificationoftenrequirestheuseofmoreadvancedanalyticaltechniquesforchemicalanalysisandspectroscopy

Identificationcriteria

must

be

based

on

the

study

of

gems

of

knownorigin(natural,synthetic,treated)

Correctidentification

must

be

based

on

multiple

criteria,

and

notjustthepresenceorabsenceofonefeature

GIA Gem Research Conference


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GIAGemResearchConference

Town&CountryResortandConventionCenter

SanDiego,

California

www.grc2009.gia.edu

GIA Research


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GIAResearch

Documents

Diamond Identification Vilnius Helsinki Aug 2008