Diamond Colour Grading

Colour Grading Diamonds

A diamond’s colour grading is a measure of how clear or yellow it is. Generally, most high-grade investment diamonds are colourless while lower-quality ones carry a yellowish tint. The more colourless your diamond is the higher its radiance, rarity, and overall perceived value. 

Diamond colour grading is based on the scale published by the Gemmological Institute of America (GIA). It goes from D (colourless) to Z (brown or yellow). The normal colour range is between D and Z. 

Diamonds with distinct colours like pink and blue diamonds are highly prized pieces while a yellowish tint on white diamonds is frowned upon. Colourless diamonds are very rare and are ranked at the top of the colour grading scale.

See below:

Diamond Colour Grading - Independent Gemmological Laboratory

The GIA Colour Grading Scale

Diamond Colour Grade Description
D The highest colour grade, D diamonds are colourless when viewed under magnification.
E E and D diamonds are almost identical to each other. Only expert gemmologists know how to differentiate the two under magnification.
F F diamonds come with nearly no visible colour. To the common man, F diamonds are identical to E and D colour diamonds. Only experienced gemmologists can tell the difference.
G To the naked eye, G diamonds appear primarily colourless.
H H diamonds are colourless to the naked eye. However, under magnification, you can see a faint yellow colour. This is noticeable especially if you compare H diamonds to higher grade ones.
I I colour diamonds appear colourless to the casual observer. These diamonds offer good value for money. You’ll barely notice the yellowish hue if you don’t view it side by side with higher grade diamonds.
J Although J colour diamonds appear colourless, you’ll notice a slight yellowish tint when you view it under magnification or bright light.
K K diamonds have a faint yellowish tint that’s visible even to the naked eye.
L L colour diamonds have a yellowish tint that’s visible in normal light.
M M colour diamonds have a definite yellow hue.
N-R Noticeable yellow or brown tint.
S-Z Easily visible brown or yellow tinting.
Diamond Colour Grading - Independent Gemmological Laboratory
Diamond Colour Grading - Independent Gemmological Laboratory

How IGL Colour Grade Diamonds

IGL takes colour grading of your diamonds to the next level. Together with the “old-fashion” system of comparing diamonds against a master set of coloured diamonds, IGL also uses the modern DC3000 Mk2 colourimeter.

The DC3000 Mk2 colourimeter reads in the GIA grading scale and helps make the process faster and more efficient by eliminating the need for manual darkfield calibration.

Manufactured by the leader and innovator in diamond spectral analysis, the Gran diamond colourimeter uses full-spectrum analysis to colour grade loose and mounted diamonds from 0.25 to 10 carats.

On the GIA-Gem Trade Lab grading scale, the Gran Diamond colourimeter measures from D through fancy intense with an accuracy of ½ of a colour grade. It also indicates the tints and hues of the stone. Unaffected by fluorescence or phosphorescence, the colourimeter features a built-in 365 nm UV light source for fluorescence testing.

Diamond Colour Grading - Independent Gemmological Laboratory
Diamond Colour Grading - Independent Gemmological Laboratory