Diamond colour guide: what is diamond colour?

Picture the perfect diamond and you’ll probably imagine a beautiful, crystal-clear stone that sparkles when it catches the light. Diamonds, however, are rarely entirely colourless and most exhibit a very subtle tint of yellow. 

This is called a diamond’s colour, and it’s one of the 4Cs of diamonds (colour, clarity, cut and carat) used to measure the quality and value of a diamond. 

• Colour is one of the 4Cs of diamonds – four scales that assess the value of a diamond based on its colour, clarity, cut and carat.
• A diamond's colour is measured on a scale from D (colourless) to Z (obvious colour).
• If a diamond has a noticeable, attractive colour, it is known as a fancy coloured diamond. 
• Lab grown diamonds are colour graded on the same scale as mined diamonds.

What is the scale for diamond colour?

Diamond colour is measured on an alphabetical scale. Created by the Gemmological Institute of America (GIA) in the 1950s, this scale is the international standard for grading the colour of all diamonds – both lab grown and natural.

The GIA colour scale grades white diamonds for their lack of colour. Grades range from D to Z, with D diamonds being entirely colourless and diamonds graded Z having a very noticeable tint.

UK diamond colour chart

What is the best colour diamond?

The best colour diamond is one with no colour at all. Colourless diamonds that score a D on the GIA colour grade scale are considered the most valuable white diamonds.

However, fancy coloured diamonds can also be extremely valuable. Certain colours are more valuable depending on the rarity of the colour.

Does diamond colour affect price?

Yes, if one diamond has a better colour grade, i.e. exhibits less colour, than another of the same carat weight, clarity and cut, then it will have a higher value.

What colour diamond is the most expensive?

In terms of white diamonds, D colour graded diamonds are the most expensive.

However, despite the popularity of white diamonds, some of the most expensive diamonds in the world are actually fancy coloured diamonds including rare pink diamonds. 

These unique coloured diamonds are graded on a different colour scale to white diamonds – from Fancy Vivid to Faint – and their rarity means they usually cost a lot more.

What is the rarest colour diamond?

The rarest colour of diamond is a red diamond. Red diamonds are so rare, in fact, that there are less than 30 of them in existence and most measure less than a carat in size.

Does diamond colour affect a diamonds sparkle?

The amount a diamond sparkles is mostly determined by its cut. However, it has been found that the brightness of a diamond diminishes in the lower colour grades and therefore reducing a diamonds sparkle.

Lab grown diamond colours

Lab grown diamonds are graded on the same colour scale as mined diamonds.

Contrary to popular belief, lab grown diamonds are not all perfectly colourless. They are real diamonds and, just like natural diamonds, they display a range of colours. 

The only difference is that there’s a better chance of controlling the colour of lab grown diamonds, due to the creation process – which means they generally have a higher-than-average score on the GIA scale.

There’s also the possibility of adding colour to the process of creating lab grown diamonds – producing unique diamonds in shades ranging from canary yellow to bright pink, blue and green.

Summary

Diamond colour is just one factor to consider when you’re shopping for a diamond. To get the best value, it’s important to balance colour with the three other Cs – cut, carat and clarity.