GIA POLISH AND SYMMETRY FEATURES Overview As you know, each GIA report contains a grade for two Finish categories: Polish and Symmetry. GIA will now provide the specific factors resulting in a given Finish grade on every diamond we grade. The information will be available online through our client portal. To ensure that our clients are familiar with the terms we use in the laboratory, we are providing a list of polish features, symmetry deviations and facet terminology with definitions and abbreviations (when applicable), that will appear in the Item Details section of My Laboratory. Please be aware that the polish and symmetry information we provide will include only grade‐setting characteristics. The list is not intended to be a prescription for receiving the grade Excellent. There may be other polish or symmetry characteristics that would prevent the diamond from receiving the grade Excellent, even if the listed characteristics are removed.
Contents Polish Features ........................................................................................................................................................................ 2 Polish Feature Locations ..................................................................................................................................................... 3 Symmetry Features ................................................................................................................................................................. 4 Abbreviations .......................................................................................................................................................................... 7
February 2012
Page 1
Polish Featu ures Polish is graded on a scale from m Excellent to o Poor based on the prese nce and visib bility of polish features at 1 10x nification. The e following fe eatures are co onsidered in tthe polish asssessment. magn Polish Feature Abraasion
Abbreviation Abr
Definition An area of minute scratch hes or pits alonng a facet edgee producing a fuzzy white line instead of a sharp facet jjunction
Burn n
Brn Dop
Whitish haze caused by e excessive heat during polishin ng or, occasionallly, by a jewelerr’s torch is listeed as “Brn.” A burn marrk caused by exxcessive heat aat the locationn where the dop tou uched the diam mond is referreed to more speecifically as “Dop.” A remnant of laser manufacturing that remains on the surface of tthe polished diamond; typicaally appears ass a transparen nt or white groo ove; only conssidered polish w when it does not penetrate into tthe diamond a t 10x magnificcation.
Laseer Man nufacturing Rem mnant
LMR
Lizard Skin
LS
A transpare ent, uneven te exture confinedd to one facet caused by polishing a facet off‐grrain
Nickk
Nck
A small nottch on a facet jjunction, usuallly along the giirdle or at the culett
Pit
Pit
A tiny open ning appearingg as a white do t
Rou ugh Girdle
RG
An irregulaar pitted or granular surface oof a bruted girdle due to pits and nicks
Scraatch
Scr
A surface m mark, normallyy seen as a finee white line thaat may be curved o or straight
Polish Lines
Wht TP Drag line Polish mark
Parallel line es left by the p polishing proceess; may appeaar white (Wht) or trransparent (TP). A heavy trannsparent polish h line off a surface‐reaching featurre is referred too more specifically as a "drag line e". A surface feature made d during the polisshing process tthat resembles an extra facet without a disttinct or straightt facet junction is referred to as a "polish markk".
Exaample
Febrruary 2012
Page 2 2
Polissh Feature Locations The location of eaach polish feature is specified using one e of the follow wing terms. Locaation Bezeel Facet Chevron Facet Crow wn Corner Step Facet Crow wn Crow wn Facet Crow wn Step Facet Culeet Gird dle Halff‐Moon Facet Low wer Half Facet Paviilion Main Facet Paviilion Paviilion Corner Sttep Faceet Paviilion Facet Paviilion Step Face et Starr Facet Table Facet Upp per Half Facet
Abb breviation Examples bezz che evron crown corner step p crown crown facet crown step cule et gird dle halff‐moon l.h. main pavv pavv corner step pavv facet pavv step starr table u.h.
Febrruary 2012
Page 3 3
Sym mmetry Fe eatures Symm metry is grade ed on a scale from Excellent to Poor baased on the p resence and vvisibility of syymmetry deviiations at 10xx magn nification. The e following fe eatures are co onsidered in tthe symmetryy assessmentt. Sym mmetry Feature e Crow wn Angle Variaation
Abb breviation CV
Definition D Unequal crown U n angles
Culeet Off‐Center
C/o oc
Deviation of th D e culet from thhe central position c n on the pavilioon
Extrra Facet
EF
Additional face A et placed withoout regard for sym r metry and nott required by the r e cutting style
Gird dle Thickness V Variation GTV V
Variation of the V e girdle thickneess
Low wer Half Percen ntage Variation
LPV V
Variation of low V wer half facet llength percentages p
Low wer Half Variation
LHV V
Unequal lower U half facet ang les
Misaalignment
Aln n
Displacement o D of the crown annd pavilion facets p in relation to eeach other o
Missshapen Facet
Facc MB B MS MM M
Difference in sh D hape or size beetween one facet and a o another of the same type, or distort t tion of a given facet; bezel, star and b main facets thhat are misshapen are m listed more specifically as m s misshapen bezzel (MB), misshapen star m r (MS) and mis shapen main (MM) m
Febrruary 2012
Exaample
Page 4 4
Sym mmetry Feature e Misssing Facet
Abb breviation MF
Definition D Asymmetrically A y missing facett
Natu ural
N
Part of the orig P ginal rough dia mond’s surface that rem s mains on the ppolished diamond d
Non n‐Octagonal Table
T/o oct
The table of a R T Round Brilliantt is not a regular octagon r n
Non n‐Pointing
Ptgg SM SB OM M OB
Fully formed fa F acet that does not reach its prescr r ribed location (short facet) or is inco f ompletely finis hed (open facet), re esulting in adjooining facets not mee f ting at precisee points; non‐pointing o n f bezel and maain facets are listed f d more specificcally as short main (SM s M), short bezel (SB), open main (OM o M) and open beezel (OB). Deviation from D m the circular shhape of a round diamo a nd; also a flatt ened area such as th a at created by aa natural, extra f n facet or unevenn girdle faceting f
Out‐‐of‐Round
OR
Paviilion Angle Varriation
PV
Unequal pavilio U on angles
Starr Percentage Vaariation
SPV V
Variation of sta V ar facet length percentages p
Exaample
Febrruary 2012
Page 5 5
Sym mmetry Feature e Starr Angle Variatio on
Abb breviation SV
Definition D Unequal star fa U acet angles
Tablle and Girdle N Not Paraallel
T/G G
Girdle plane no G ot parallel to thhe table
Tablle Off‐Center
T/o oc
Deviation of th D e table from thhe central position c n on the crownn
Tablle/Culet Alignm ment
T/C C
Displacement o D of the table faccet and culet in opposit c te directions
Upp per Half Variation
UHV V
Unequal upper U r half facet anggles
Uneeven Outline
UO
Asymmetrical s A shape outline
Wavvy Girdle
WG G
Undulating gird U dle
Febrruary 2012
Exaample
Page 6 6
Abbreviations POLISH FEATURES
POLISH LOCATIONS
Abbreviation Abr Brn Dop LMR LS Nck Pit RG Scr Wht TP Drag line Polish mark
Abbreviation bez chevron crown corner step crown crown facet crown step culet girdle half‐moon l.h. main pav pav corner step pav facet pav step star table u.h.
*Reports for all diamonds graded later than January 30th, 2012 should include only the terminology and abbreviations listed in this document. You may come across non‐standardized information on diamonds graded prior to January 30th, 2012 including the use of the modifiers listed in the table above. “Sl” and “+” were typically applied to both Polish features and Symmetry deviations, while “fnt” and “hvy” were applied exclusively to Polish features. The modifier “+” referred to multiple facets of the same type with a given polish feature, or multiple facets of the same type with a given symmetry deviation (Ex. TP: l.h.+; MM+).
