Diamond Grading

Diamonds are assessed according to the four Cs:

Carat weight

1 carat equals 0.2 grams.


The quality of a cut is assessed in terms of its proportions, symmetry and polish.


Unless regarded as a ‘fancy’ coloured diamond, all diamonds are graded on their lack of colour. The gradings runs as follows:

GIA CIBJO Traditional
D Exceptional White + (EW+) Finest White
E Exceptional White (EW) Finest White
F Rare White + (RW+) Fine White
G Rare White (RW) Fine White
H White (W) White
I Slightly Tinted White (STW) Commercial White
J Slightly Tinted White (STW) Top Silver Cape
K Tinted White (TW) Top Silver Cape
L Tinted White (TW) Silver Cape
M-Z Tinted Colour (TC) Cape
Fancy Fancy Colour


Diamonds are graded on their freedom from inclusions (within the stone) and blemishes (found on the surface of the stone). They are assessed using 10x magnification, and are graded as follows:

GIA CIBJO Description
Flawless (FL) Loupe Clean (LC) Shows no inclusions or blemishes
Internally Flawless (IF) Loupe Clean (LC) Shows no inclusions and only insignificant blemishes
Very Very Slightly Included (VVS1/2) Very Very Slightly Included (VVS1/2) Contains minute inclusions which are very difficult for an experienced grader to see with 10x magnification
Very Slightly Included (VS1-2) Very Slightly Included (VS1-2) Contains very small inclusions that are difficult to see with 10x magnification
Slightly Included (SI1-2) Slightly Included (SI1-2) Slightly Included Contains inclusions that are easily visible with 10x magnification
Imperfect/Included (I1-3) Pique (P1-3) Contains inclusions that are obvious with 10x magnification and can often been seen with the naked eye; durability may be affected

Please note the four Cs of a diamond cannot be fully assessed whilst the stone is mounted. The approximate gradings provided in the condition reports are estimations, made by the specialists whilst the stones were mounted and are for guidance only. If a stone has been unmounted and assessed in a gemmological laboratory, this will be noted in the cataloguing/condition report.