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Diamond Identification Vilnius Helsinki Aug 2008

Apr 03, 2018

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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