Diamond Colour Grades D to Z Explained

Diamond colour is the absence of colour. The less colour a white diamond has, the higher its grade. The scale looks like alphabet soup, but it is easy to follow once you know the bands.

The scale

Colour is graded on a scale that starts at D, the highest, and runs down to Z. The grades fall into bands:

• D, E, F: colourless.
• G, H, I, J: near colourless.
• K, L, M: faint colour.
• N to R: very light colour.
• S to Z: light colour.

Grades are assigned in a controlled setting, with the diamond examined face-down against a white background alongside master stones for comparison.

Why D is not the point

Diamonds at the top of the scale are rarer and cost more. But the differences between neighbouring grades are subtle, often detectable only by an expert comparing loose stones side by side under controlled lighting. Once set in jewellery, the metal and the surroundings affect what you see.

Colour and metal

• White metals (white gold, platinum): reflect a cool tone, which helps a colourless stone look icy. A very slight tint is more noticeable against them, so many buyers choose D to H for solitaires in white metal.
• Yellow and rose gold: their warm tone picks up in the stone, and a near-colourless stone looks beautifully white in them. A grade in the G to J range often looks very similar to a higher grade, and costs less.

See rose gold, white gold and yellow gold: how to choose.

Shape matters too

Round brilliants hide colour well because of their sparkle. Step cuts, such as emerald and Asscher, show colour more clearly. Larger stones show colour more than small ones.

What about "fancy" colours?

Diamonds with strong natural colour, such as pink, blue or deep yellow, are graded on a separate fancy colour scale. They are a separate category and are priced differently.

How to choose a grade

1. Decide the metal. Warm metals forgive lower grades.
2. Decide the size. The bigger the stone, the more colour shows.
3. See the stones in daylight and under shop light.
4. Compare a stone one grade up and one grade down.
5. Spend your budget where you notice the difference. Often that is cut quality, not colour.

Reading the grade on a certificate

The colour grade is one box on the report. See how to read a diamond certificate step by step for the other boxes.

A closer look at a few practical points

Lighting changes how colour looks. Under warm bulbs, a near-colourless stone can look warmer than it does in daylight. Look at it in more than one light.

Colour grading is done on loose stones. Once a stone is set, the surrounding metal and other stones make a one-grade difference hard to see.

Budget advice. If you are choosing between two stones and one is one colour grade higher but much more expensive, ask yourself whether the difference is visible to you when the stone is on your hand. If not, put the money into a better cut or a slightly larger stone.

Cloudy or milky looks are not colour. A diamond that looks dull may have a cut or clarity issue, or fluorescence, rather than a low colour grade.

Seeing is believing

Photographs cannot show subtle colour differences. If you want to compare grades, book an appointment. To see a range of stones set in 18K yellow gold, browse our diamond pendants.