8. diamond grading

7/27/2019 8. Diamond Grading

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DIAMOND GRADING:DIAMOND GRADING:

estimation of the quality andestimation of the quality and

value of diamondsvalue of diamonds

Univ.Prof.Dr.CorinaUniv.Prof.Dr.CorinaIonescuIonescu

20112011

Universitatea Babes-Bolyai Cluj-Napoca. Catedra de Mineralogie. No reproduction, copy or transmission of this

file or part of this file may be made without permission of the author. The file is only for internal use in the Chair of

Mineralogy, Babes-Bolyai University of Cluj-Napoca, Romania.


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General dataGeneral data

DefinitionDefinition: estimation of the quality of diamonds: estimation of the quality of diamonds(classification in quality classes) and estimation of the(classification in quality classes) and estimation of the

value (price)value (price)

SuitableSuitable only natural diamondsonly natural diamonds::

Cut diamondsCut diamonds

Loose stonesLoose stones

LaserLaser--drilled diamondsdrilled diamonds

NotNot for:for: Treated (irradiated, dyed, HTHP) diamondsTreated (irradiated, dyed, HTHP) diamonds

Synthetic diamondsSynthetic diamonds

Rough stonesRough stones

FractureFracture--filled diamondsfilled diamonds


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International Diamond CouncilInternational Diamond Council

rulesrules 10x loupe10x loupe

Artificial lightArtificial lightequivalent to day lightequivalent to day light

(3 bulbs each of 8 watt(3 bulbs each of 8 watt))


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General dataGeneral dataMain parts of a brilliantMain parts of a brilliant--cut diamondcut diamond


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Order of observation:Order of observation: crowncrown

pavilionpavilion

side (girdle)side (girdle)


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Order of observation:Order of observation:

crowncrown

pavilionpavilion



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Order of observation:Order of observation: crowncrown

pavilionpavilion



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I. Estimation ofI. Estimation of

the qualitythe quality

classesclasses


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The 4 cThe 4 c

1. Colour1. Colour

2. Clarity2. Clarity3. Cut3. Cut

4. Carat4. Carat


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1.1. ColourColour


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Colour grading: 6 classesColour grading: 6 classes

based on the increasing yellowbased on the increasing yellow

saturationsaturation

EW RW W STW TW TC


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Colour gradingColour grading


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Colour gradingColour grading

Six Master stones: cubic zirconiaSix Master stones: cubic zirconia

(synthetic product):(synthetic product): EW, RW, W, STW,EW, RW, W, STW,

TW, TCTW, TC


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ColourColourgradinggrading

GIA (Gemological Institute of America)GIA (Gemological Institute of America)colourcolourgrading scalegrading scale


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Colour gradingColour gradingSSyymmbboollss ffoorrccoolloouurr

ggrraaddiinngg ((GGIIAA

ssyysstteemm))

CCoolloouurrccllaasssseess

uusseedd tt ii ll ll 11999900CCoolloouurrccllaasssseess

((aaccttuuaall ssyysstteemm,,

EEuurrooppee))

SSyymmbboollss ffoorr

ccoolloouurrccllaasssseess

((EEuurrooppee))DE River Exceptional white EW

FG Top Wesselton Rare white RW

H Wesselton White WI Top CrystalJ Crystal Slightly tinted white STW

KL Top Cape Tinted white TW

M O CapeZ Yellow

Tinted colour(Light yellow)

TC1TC4

Fancy diamonds(All colours)


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2. Clarity2. Clarity


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Clarity gradingClarity grading


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Internal featuresInternal features: inclusions, cracks,structural planes

External featuresExternal features [scratches, polishing

lines, pits, cavities, natural faces(remnants), structural lines] which may

decrease the clarity


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Clarity gradingClarity grading:: inclusionsinclusions

- inclusions / solid, liquid, gas

- cracks- growth lines

- twinning planes

- cleavage planes


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Clarity grading:Clarity grading: 77 classesclasses

LCLC orIFIF (Loupe clean or Internally

flawless)

VVSVVS (Very very small inclusions)

VSVS (Very small inclusions) SISI (Small inclusions)

P1P1 (Pique 1)

P2P2 (Pique 2)

P3P3 (Pique 3)


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Clarity grading:Clarity grading: LCLC (Loupe(Loupeclean) classclean) class

(or IF(or IF -- Internally flawless)Internally flawless)

Free from anyFree from any inclusioninclusion at 10X loupe,at 10X loupe,

nothing to be seen respectively;nothing to be seen respectively;

In USA no external defects areIn USA no external defects areaccepted;accepted;

In Europe only external features whichIn Europe only external features which

do not diminish the clarity, aredo not diminish the clarity, areaccepted: small cleavage cracks alongaccepted: small cleavage cracks along

the girdle, growth lines, twinning lines.the girdle, growth lines, twinning lines.


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Clarity grading:Clarity grading:

LCLC (Loupe clean) class(Loupe clean) class


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VVSVVS classclass(Very very small inclusions)(Very very small inclusions)

Very, very smallVery, very small inclusionsinclusions,,

difficult to be seen with 10X loupedifficult to be seen with 10X loupe The nature of theThe nature of the inclusionsinclusions isis

impossible to be find only with 10Ximpossible to be find only with 10Xloupeloupe


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Cl it di


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Cl i diCl it di


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Cl it diCl it di


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Cl it diCl it di


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Cl it diCl it di


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VSVS classclass(Very small inclusions)(Very small inclusions)

Very smallVery small inclusionsinclusions, which, which

are difficult to be seen withare difficult to be seen with10X loupe10X loupe

Cl it diClarit grading


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Clarit gradingClarity grading:


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SISI classclass(Small inclusions)(Small inclusions)

SmallSmall inclusionsinclusions, easily to be, easily to be

seen with 10X loupe butseen with 10X loupe but

invisible with naked eyeinvisible with naked eye

The presence ofThe presence ofinclusionsinclusions dodo

not diminish the brilliance of thenot diminish the brilliance of the

diamonddiamond



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Clarity grading:y g g

P1P1 class (Pique 1)class (Pique 1)or Imperfect 1or Imperfect 1

Inclusions visible by naked eye, easilyInclusions visible by naked eye, easily

to be identified with 10X loupeto be identified with 10X loupe The inclusions do not diminish theThe inclusions do not diminish the

clarity/brilliance of the diamondclarity/brilliance of the diamond


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Clarity grading:Clarity grading:P1P1 class (Pique 1)class (Pique 1)


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Clarity grading:Clarity grading:P1P1 classclass (Pique 1)(Pique 1)


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y g g

P2P2 classclass (Pique 2)(Pique 2)or Imperfect 2or Imperfect 2

Numerous and/or largerNumerous and/or largerinclusionsinclusions,,

easily to be seen with naked eye;easily to be seen with naked eye;

thethe inclusionsinclusions lightly diminish thelightly diminish the

clarity/brilliance of the diamond.clarity/brilliance of the diamond.


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P3P3 class (Pique 3)class (Pique 3)or Imperfect 3or Imperfect 3

Larger and/or numerousLarger and/or numerous inclusionsinclusions

easily seen with naked eye;easily seen with naked eye; TheThe inclusionsinclusions strongly diminish thestrongly diminish the

clarity/brilliance of the diamond.clarity/brilliance of the diamond.


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Clarity grading:Clarity grading:P3P3 classclass (Pique 3)(Pique 3)

Clarity grading:


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Clarity grading:C a y g ad g

P3P3 class (Pique 3)class (Pique 3)

Clarity grading:


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Clarity grading:y g g


Clarity grading


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Clarity gradingy g g



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The 4 cThe 4 c

3. Cut3. Cut


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Cut gradingCut grading

A. ProportionsA. Proportions

B. Symmetry featuresB. Symmetry features

C. Polishing quality (finishing)C. Polishing quality (finishing)


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B. Symmetry featuresC. Polishing quality (finishing)


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Cut grading: proportionsCut grading: proportions

Table diameterTable diameter

Crown angleCrown angle

Pavilion depthPavilion depth


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Cut grading: proportionsCut grading: proportionsPPrrooppoorrtt iioonnss MMeeddiiuumm ttoo

ppoooorrGGoooodd VVeerryy ggoooodd GGoooodd MMeeddiiuumm

ttoo ppoooorr

Table diameter < 53% 53 55% 56 66% 67 70% > 70%

Crown height < 9% 9 10% 11 15% 16 17% > 17%

Crown angle < 27o

27 30o 31 37o 38 40o > 40o

Pavilion depth < 40% 40 41% 42 - 45% 46 47% > 47%

Girdle thickness Extremelythin

Very thin Thin tomedium (2-

4%)

Thick Very thick

Culet size Large(3-4%)

or no culet

Small tomedium

(2%)

Small (1%) Small tomedium

(2%)

Large(3-4%) orno culet

C di iC di i


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C t di tiC t di ti


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C t di tiC t di ti


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Empiric estimation: table diameter ~ 54%Empiric estimation: table diameter ~ 54%

C t di tiC t di ti


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C t grading proportionsC t grading proportions


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Empiric estimation: crown angleEmpiric estimation: crown angle



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Empiric estimation: girdle thicknessEmpiric estimation: girdle thickness


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Empiric estimation: culet sizeEmpiric estimation: culet size

No culetNo culet


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Small culetSmall culet


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Medium culetMedium culet


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Very large culetVery large culet


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Cut grading: proportionsCut grading: proportionsEmpiric estimation:Empiric estimation: very good brill iancevery good brill iance

(very good proportions(very good proportions -- pavilion of 43pavilion of 43--44%)44%)



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Empiric estimation:Empiric estimation: good brilliancegood brilliance (good(good

proportionsproportions --pavilion 46%)pavilion 46%)



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Cut grading: proportionsCut grading: proportionsEmpiric estimation:Empiric estimation: Medium brillianceMedium brilliance

(good proportions(good proportions --pavilion 48%)pavilion 48%)



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Cut grading: proportionsCut grading: proportionsEmpiric estimation:Empiric estimation: medium brill iancemedium brill iance

(medium proportions(medium proportions--pavilion about 48%)pavilion about 48%)



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Empiric estimation:

poor brilliancepoor brilliance

(poor proportions

- too shallow

pavilion,


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Cut grading: symmetryCut grading: symmetry


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A.A. ProportionoscopeProportionoscope: measurable: measurable

featuresfeatures

-- Deviation from a perfect round shapeDeviation from a perfect round shape

of the girdle (off round)of the girdle (off round)-- Table parallel to the girdle planeTable parallel to the girdle plane

-- Eccentric table or/and culetEccentric table or/and culet



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g g y yg g y y

B. 10X loupe: notB. 10X loupe: not--measurable features:measurable features:

--Asymmetric tableAsymmetric table

--Asymmetric culetAsymmetric culet

-- Facets of unequal sizeFacets of unequal size-- Unequal thickness of the girdleUnequal thickness of the girdle

-- Missing the meetMissing the meet--point of the facetspoint of the facetsedgesedges



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g g y yg g y y



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g g y yg g y y



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g g y yg g y y



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g g y yg g y y



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g g y yg g y y



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g g y yg g y y


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Cut grading: finishingCut grading: finishing--

polishingpolishing


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Cut grading: finishingCut grading: finishing--

polishingpolishing


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QQuuaalliittyy oofftthhee

ssuurrffaaccee

PPoolliisshhiinngg

qquuaalliittyyWithout any polishinglines

Very good

Few polishing lines Good

Numerous and visiblepolishing lines

Medium

Polishing lines whichdiminish the brilliance ofthe diamond

Poor

The 4 cThe 4 c


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4. Carat4. Carat

Carat gradingCarat grading


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Mass (Mass (weightweight): carat): carat

1 ct = 0.215 g1 ct = 0.215 g

1ct = 100 points1ct = 100 points

Weighting: balance, scaleWeighting: balance, scale

Mass (carat) = diameterMass (carat) = diameter22 x total depth xx total depth x

0.0061 (up to 0.0064)0.0061 (up to 0.0064)

Carat gradingCarat grading


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The value: onlyThe value: only

recalculated massrecalculated mass

(measured mass minus the deductions(measured mass minus the deductions

due to the deviation from idealdue to the deviation from idealproportions, symmetry and polishing)proportions, symmetry and polishing)

BABE-BOLYAI UNIVERSITY CLUJ-NAPOCAFACULTY OF BIOLOGY AND GEOLOGYGEMOLOGICAL LABORATORYNr._____________________-

DIAMOND GRADING REPORT


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Cut style and shape: brilliant, roundDimension_____________________mmMass (weight)__________________ct

PROPORTIONS_________________

Table (%) Crown height(%) Pavilion depth (%)

________ _________ __________

Girdle_____________________Culet______________________

FINISHING______________________

Polishing________________Symmetry_______________

CLARITY_________________

COLOUR___________________

Visual________________Photometric_____________Luminiscence___________

COMENTS

Red coloured symbols represent internal features.Green coloured symbols represent external features.The symbols indicate the nature and position of thefeatures and not necesarly their size.

DIAMOND EXPERTName ________________________

Signature _____________________

Data__________________________


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II. ValueII. Value

Base for evaluation: value of

an ideal diamondWW--LCLC: white, loupe clean


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, p

MMaassss (( wweeiigghhtt )) PPrriiccee ppeerrcctt ((nn $$)) ffoorr11999999

0,18 0,19 ct 900

0,30 0,32 ct 2.300

0,40 0,42 ct 2.600

0,50 0,59 ct 2.800

0,70 0,74 ct 2.950

0,94 0,95 ct 3.200

0,96 ct 3.300

0,97 ct 3.400

0,98 ct 3.500

0,99 ct 3.600

1,00 ct 4.000

Ratio (%) between the idealRatio (%) between the ideal

diamond value and otherdiamond value and otherdiamondsdiamonds


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LC VVS VS SI P1 P2 P3

Exceptional white(EW)

170 140 100 70 60 50 35

Rare white (RW) 140 100 90 65 50 40 30

White (W) 100 80 75 60 45 35 25

Slightly tintedwhite (STW)

80 70 65 55 35 30 20

Tinted white (TW) 70 60 45 35 25 20 15

Tinted colour(TC2)

50 40 30 25 20 15 10


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Eureka diamondEureka diamond


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GuineeaGuineea Star diamondStar diamond


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PrincessePrincesse cut diamondcut diamond


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8. diamond grading

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