Naturally coloured diamonds are rare and expensive. Diamonds gets their colour from trace elements or internal structural anomalies in the diamond. Yellow is the most common coloured diamond while pink (Argyle Pink Diamonds), red, blue and green diamonds are extremely rare. Fancy colour diamonds are cut to maximise colour and not clarity as with typical white diamonds.
Of the 4Cs, colour is the most important property for these stones. Generally, the higher the saturation of colour, the more valuable the stone is.
Diamond Colour Properties
The strength of a diamond’s colour is created from the combination of;
- Hue: The predominant colour
- Tone: The darkness of colour
- Saturation: The intensity of the colour.
How Diamonds get their particular colours
- Brown: A brown colour is caused by a distortion of the atomic structure of the stone. These diamonds vary in shades from champagne to cognac.
- Yellow: Yellow diamonds get their colour from the presence of nitrogen.
- Blue: Blue diamonds are created from trace elements of boron in their structure. The 45.53 carat Hope Diamond is an example of a blue diamond.
- Pink: Pink diamonds owe their colouring to a phenomenon in the crystal lattice structure of the diamond. The Argyle diamond mine in Western Australia produces 90% of the world’s supply of pink diamonds.
- Green: Green diamonds were exposed to natural radiation as they were forming billions of years ago, thus earning their colour.
GIA Colour Grading
GIA uses specific grades for coloured diamonds and their colouring, these are;
- Very Light
- Fancy Light
- Fancy Intense
- Fancy Vivid
- Fancy Dark
- Fancy Deep