For white diamonds, colour grading is really about the absence of colour. The closer a diamond is to colourless, the higher its grade. Most white diamonds show a faint yellow or brown tint, often so subtle that it can only be seen when stones are compared side by side.
The D-to-Z scale
| Grades | Group | What you see |
|---|---|---|
| D, E, F | Colourless | No colour visible |
| G, H, I, J | Near colourless | Colour difficult to detect, especially once set |
| K, L, M | Faint | A faint warmth may be visible |
| N to R | Very light | Light colour visible |
| S to Z | Light | Colour clearly visible |
Grading is done by comparing a diamond with master stones under controlled lighting, usually looking from the side, where colour is easiest to judge.
What changes the colour you see
- Metal: white gold and platinum emphasise whiteness and can reveal warmth; yellow and rose gold complement warmer grades.
- Shape: colour can concentrate at the ends of elongated shapes and is more visible in step cuts.
- Size: colour is easier to see in larger stones.
Fluorescence
Some diamonds glow, most often blue, under ultraviolet light. Reports describe its strength from None to Very Strong. In most cases it has no visible effect in normal light; occasionally, very strong fluorescence can make a stone look slightly hazy.
Fancy coloured diamonds
Diamonds with distinct colour, such as yellow, pink or blue, are graded on a different system that describes hue, tone and saturation, with terms such as Fancy Light, Fancy Intense and Fancy Vivid.
A practical guide by metal
Many people find that near-colourless grades look white once set, especially in yellow or rose gold, which reflect warmth into the stone. In white gold or platinum, a warm tint is easier to notice, so colourless or high near-colourless grades are often preferred. These are tendencies, not rules: the best test is to look at the stone in the metal you have chosen.
Colour in laboratory-grown diamonds
Laboratory-grown diamonds are graded on the same D-to-Z scale. Many CVD diamonds are treated after growth to remove a brownish tint, and some HPHT diamonds can show a faint blue or grey tone. Reports describe colour in the same terms and note treatments where detected.
How to judge colour yourself
- Look at the stone against a plain white background, in daylight or neutral light.
- View it from the side as well as from above.
- Compare it with another stone of a known grade if you can.
- Remember that jewelry lighting in shops is designed to flatter.
Sources: Gemological Institute of America (gia.edu), the 4Cs of diamond quality and GIA grading scales.
Frequently asked questions
Can I see the difference between D and G?
Rarely once set, and almost never without comparing stones side by side. Differences between neighbouring grades are subtle.
What colour looks best in yellow gold?
Yellow and rose gold complement warmer grades, so a near-colourless diamond often looks white in them.
Is a D colour diamond better?
It is the rarest and whitest grade. Whether it is better for you depends on what you can see and what you value; in a setting, the difference from E or F is very hard to see.
Do lab-grown diamonds come in D colour?
Yes. Laboratory-grown diamonds span the colour scale, and colourless grades are common.
