Diamond Polish and Symmetry: Guide to GIA Terminology and Abbreviations

Every GIA diamond grading report contains an assessment of a diamond’s polish and symmetry, which are contributing factors in determining the overall quality of a diamond’s finish. In evaluating polish and symmetry, GIA considers their specific features and visibility under 10x magnification. Polish and symmetry are then rated on a scale ranging from Excellent to Poor.
 
The guide below explains each polish and symmetry feature, along with their abbreviations and the possible locations of polish features on the diamond.
 
Laboratory clients can view the detailed polish and symmetry assessment for each diamond they submit, by going to the Item Details in My Laboratory.
 

Polish Features

Polish is graded on a scale from Excellent to Poor based on the presence and visibility of polish features at 10x magnification. The following features are considered in the polish assessment.

Polish Feature Abbreviation Definition Example
Abrasion Abr An area of minute scratches or pits along a facet edge producing a fuzzy white line instead of a sharp facet junction
Burn Brn
Dop
Whitish haze caused by excessive heat during polishing or, occasionally, by a jeweler’s torch is listed as “Brn.”

A burn mark caused by excessive heat at the location where the dop touched the diamond is referred to more specifically as “Dop.”
Laser Manufacturing Remnant LMR A remnant of laser manufacturing that remains on the surface of the polished diamond; typically appears as a transparent or white groove; only considered polish when it does not penetrate into the diamond at 10x magnification.
Lizard Skin LS A transparent, uneven texture confined to one facet caused by polishing a facet off-grain
Nick Nck A small notch on a facet junction, usually along the girdle or at the culet
Pit Pit A tiny opening appearing as a white dot
Rough Girdle RG An irregular pitted or granular surface of a bruted girdle due to pits and nicks
Scratch Scr A surface mark, normally seen as a fine white line that may be curved or straight
Polish Lines Wht
TP
Drag line
Polish mark
Parallel lines left by the polishing process; may appear white (Wht) or transparent (TP). A heavy transparent polish line off a surface-reaching feature is referred to more specifically as a "drag line".

A surface feature made during the polishing process that resembles an extra facet without a distinct or straight facet junction is referred to as a "polish mark".


Polish Feature Locations

The location of each polish feature is specified using the following terms.

Location Abbreviation
Bezel Facet bez
Chevron Facet chevron
Crown Corner Step Facet crown corner step
Crown crown
Crown Facet crown facet
Crown Step Facet crown step
Culet culet
Girdle girdle
Half-Moon Facet half-moon
Lower Half Facet l.h.
Pavilion Main Facet main
Pavilion pav
Pavilion Corner Step Facet pav corner step
Pavilion Facet pav facet
Pavilion Step Facet pav step
Star Facet star
Table Facet table
Upper Half Facet u.h.

Examples:
View Gallery

Symmetry Features
Symmetry is graded on a scale from Excellent to Poor based on the presence and visibility of symmetry deviations at 10x magnification. The following features are considered in the symmetry assessment.

Symmetry Feature Abbreviation Definition Example
Crown Angle Variation CV Unequal crown angles
Crown Height Variation CHV Girdle plane not parallel to the table causing uneven crown height
Culet Off-Center C/oc Deviation of the culet from the central position on the pavilion
Extra Facet EF Additional facet placed without regard for symmetry and not required by the cutting style
Girdle Thickness Variation GTV Variation of the girdle thickness at the bezel-main positions
Lower Half Percentage
Variation
LPV Variation of lower half facet length percentages
Lower Half Variation LHV Unequal lower half facet angles
Misalignment Aln Displacement of the crown and pavilion facets in relation to each other
Misshapen Facet Fac
MB
MS
MM
Difference in shape or size between one facet and another of the same type, or distortion of a given facet; bezel, star and main facets that are misshapen are listed more specifically as misshapen bezel (MB), misshapen star (MS) and misshapen main (MM)
Missing Facet MF Asymmetrically missing facet
Natural N Part of the original rough diamond’s surface that remains on the polished diamond
Non-Octagonal Table T/oct
TEV
The table of a Round Brilliant is not a regular octagon, showing differences among the four table sizes (T/oct) or among the eight table edges (TEV)
Non-Pointing Ptg
SM
SB
OM
OB
Fully formed facet that does not reach its prescribed location (short facet) or is incompletely finished (open facet), resulting in adjoining facets not meeting at precise points; non-pointing of bezel and main facets are listed more specifically as short main (SM), short bezel (SB), open main (OM) and open bezel (OB)
Out-of-Round OR Deviation from the circular shape of a round diamond
Pavilion Depth Variation PDV Variation of pavilion depth
Pavilion Angle Variation PV Unequal pavilion angles
Star Percentage Variation SPV Variation of star facet length percentages
Star Angle Variation SV Unequal star facet angles
Table Off-Center T/oc Deviation of the table from the central position on the crown
Table/Culet Alignment T/C Displacement of the table facet and culet in different directions
Upper Half Variation UHV Unequal upper half facet angles
Uneven Outline UO Asymmetrical shape outline; also refers to bumps and flattened areas created by a natural, extra facet or uneven girdle faceting on round diamonds 

Cumulative

Cumulative is listed under symmetry features when the symmetry grade is based on the combined effect of symmetry features instead of individual deviations. For example, a diamond with pavilion depth variation (PDV) and crown angle variation (CV) that measures on the border of Very Good and Good may receive a lower symmetry grade based on their combined appearance and be represented as “Cumulative: PDV, CV.”


Abbreviations
Polish Features  
Abbreviation Polish Feature
Abr Abrasion
Brn Burn
Dop Dop Burn
LMR Laser Manufacturing Remnant
LS Lizard Skin
Nck Nick
Pit Pit
RG Rough Girdle
Scr Scratch
Wht White Polish lines
TP Transparent Polish Lines
Drag line  
Polish mark  

Symmetry Features  
Abbreviation Symmetry Feature
Aln Misalignment
C/oc Culet Off-Center
CV Crown Angle Variation
CHV Crown Height Variation
EF Extra Facet
Fac Misshapen Facet
GTV Girdle Thickness Variation
LHV Lower Half Angle Variation
LPV Lower Half Percentage Variation
MB Misshapen Bezel
MF Missing Facet
MM Misshapen Main
MS Misshapen Star
N Natural
OB Open Bezel
OM Open Main
OR Out-of-Round
PDV Pavilion Depth Variation
Ptg Non-Pointing
PV Pavilion Angle Variation
SB Short Bezel
SM Short Main
SPV Start Percentage Variation
SV Star Angle Variation
T/C Table/Culet Alignment
T/oc Table Off-Center
T/oct Non-Octagonal Table
TEV Table Edge Variation
UHV Upper Half Angle Variation
UO Uneven Outline

Polish Locations  
Abbreviation Polish Location
bez Bezel Facet
chevron Chevron Facet
crown corner step Crown Corner Step Facet
crown Crown 
crown facet Crown Facet
crown step Crown Step Facet
culet Culet
girdle Girdle
half-moon Half-Moon Facet
l.h. Lower Half Facet
main Pavilion Main Facet
pav Pavilion
pav corner step Pavilion Corner Step Facet
pav facet Pavilion Facet
pav step Pavilion Step Facet
star Star Facet
table Table Facet
u.h. Upper Half Facet

Modifiers*  
Abbreviation Modifier
sl slight
fnt faint
hvy heavy
+ multiple

*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+).


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