Ask Neil: Diamond colour explained

Ask Neil: Diamond colour explained

"I've heard that colour is one the 'Four C's' and an important consideration when buying. What exactly should I look out for - and aren't the majority of stones without colour anyway?"

- Richard, St. Mellons

"Standard “white” diamonds are graded using the GIA’s alphabetic scale, shown below, with D offering the least discolouration (meaning a presence of yellow hue in the stone) and Z the most.

Typically the commercial grades available on the high street will be G-H, unless you are really looking to spend some money!

In all honesty, any grade between D and J will appear virtually colourless to the casual eye. You could probably discern a subtle difference in say, E, F and G stones when placed next to each other, but otherwise all 3 will present very similar, bright white hues.

Stones in the I-J range will also be available at a lower price, with incrementally more discolouration, while stones graded K and lower are a lot less commonly sold new – these are more effectively used to support higher grade stones in an item of jewellery, and not as centrepieces themselves.

“Fancy-coloured” diamonds are stones with non-yellow hues, such as red, green or blue, and have separate systems for colour grading which are more complex.

The GIA estimates that 1 in 10,000 diamonds found are fancy-coloured, and for some of the rarest colours, such as red, only a few dozen have ever been found. The images below show how a rough yellow diamond is transformed using a radiant cut.

Fancy stones are extremely rare, and highly expensive, so purchase these only from a trusted supplier or expert!

Overall, the way in which diamonds are sold to the public has changed in the last decade, with online retailers such as Blue Nile and 77 Diamonds offering stones to a wide customer base at trade prices, and concepts such as the 4 C’s are sometimes exaggerated in their importance as a marketing tactic.

While this system is still used internally by traders to help value diamonds in a consistent way, like with other aspects of gemology, it shouldn’t be the only thing you consider."


Neil Rayment is a Goldsmith-accredited fine jewellery and metalcraft expert with over 30 years of experience in the industry. 
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