The colour of a diamond is determined by chemical impurities and/or structural defects. Depending on the hue and intensity of a diamond’s colouration, a diamond’s colour can either detract from or enhance its value. When jewellers speak of a diamond’s colour, they are usually referring to the presence or absence of colour in white diamonds. Colour is a result of the composition of the diamond, and it never changes over time.
The formation process of a diamond ensures that only a few, rare diamonds are truly colourless. So the whiter a diamond’s colour, the greater is its value.
TIP: Diamonds graded G through I show virtually no colour that is visible to the untrained eye.
[NOTE: Fancy colour diamonds do not follow this rule. These diamonds, which are very rare and very expensive, can be any colour from blue to green to bright yellow. They are actually more valuable for their colour.]
To grade ‘whiteness’ or colourlessness, most jewellers refer to GIA’s professional colour scale that begins with the highest rating of D for colourless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish colour. The colour scale continues all the way to Z.
Which Colour Grade Should I Choose?
Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colourless. While a very, very faint hint of yellow will be apparent in diamonds graded J through M, this colour can often be minimized by carefully selecting the right jewellery in which to mount your diamond. Keep in mind that, while most people strive to buy the most colourless diamond they can afford, there are many people who actually prefer the warmer glow of lower-colour diamonds.
TIP: Diamonds graded G through I show virtually no colour that is visible to the untrained eye. If you are setting your diamond in white gold or platinum you may wish to opt for a higher colour grade than if the setting is yellow gold.
What is Fluorescence?
Fluorescence is an effect that is seen in some gem-quality diamonds when they are exposed to long-wave ultraviolet light (such as the lighting frequently seen in dance clubs). Under most lighting conditions, this fluorescence is not detectable to the eye. While most gemmologists prefer diamonds without this effect, some people enjoy it. It’s really just a matter of aesthetics.