From a perfectly colourless diamond to one with a slight yellow tint, colour is the criterion that most directly influences a stone's visual brilliance, and one of the most cost-effective to choose well.
The scale starts at D: there's no "A", "B" or "C" grade, a deliberate choice by GIA to distance itself from unreliable old commercial scales. D denotes absolute colourlessness, the rarest; Z denotes a yellow or brown tint visible to the naked eye.
| Grade | D | E | F | G | H | I-J | K-M | N-Z |
|---|---|---|---|---|---|---|---|---|
| HRD denomination | Exc. White+ | Exc. White | Rare White+ | Rare White | White | Sl. Tinted White | Tinted White | Tinted Colour |
Once set, the difference between D and G is virtually impossible to perceive with the naked eye, even a trained one, especially in yellow or rose gold, which further masks a slight tint. This is why many connoisseurs consider G-H the best value for money, reserving D-E-F for exceptional stones or platinum and white gold settings that reveal everything.
D is the rarest grade and the most sought-after by collectors and investors: it's the very reason for my D Collection. A certified D-colour stone holds its value over time better than any other grade, and remains a universal benchmark of excellence in colourless diamonds.
Some diamonds emit a faint blue glow under ultraviolet light: this is fluorescence, noted on the certificate separately from colour. Faint or medium fluorescence generally goes unnoticed day to day, and can even make a slightly tinted stone (K, L) look whiter to the eye. Strong fluorescence, on the other hand, can give an otherwise very white stone (D to F) a hazy appearance: this is the one case where I recommend caution.
View the D Collection →G or H offer the best balance: the stone appears white to the naked eye, without paying the premium for D-E-F grades, which mostly matter to a collector or a stone set in platinum.
Only when comparing two stones side by side, under good lighting, and even then, from two or three grades apart. Once the stone is alone on a finger, most people can't tell G from I.
Yes, partly. Yellow gold reflects a warm tone that makes a slight diamond tint much less visible, which often allows you to go one or two grades lower without a visual trade-off, unlike white gold or platinum, which reveal everything.
It's a faint glow emitted under ultraviolet light, noted separately on the certificate. Faint or medium fluorescence goes unnoticed day to day; strong fluorescence can give very white stones a hazy appearance.
It's a deliberate choice by GIA, to clearly distance itself from unreliable old commercial scales that already used A, AA or AAA with no shared standard.
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