Diamonds can occur in almost any colour imaginable. Often the colour differences are subtle, but every stone is individual and unique.
Natural fancy coloured diamonds are the most valuable because of their rarity. For every 10 000 carats of diamonds mined, only 1 carat is coloured. Since recorded history, coloured diamonds have embodied all that is most valuable in the world and have traditionally been collectors' pieces and objects of art in their own right.
Coloured diamonds are created when atoms of an element other than carbon are added to a diamond. The colour is determined by the element added as well as changes in temperature and pressure. The colour produced is a product of chance and no two diamonds are exactly the same. It is this unique rareness that gives them their value.
When nitrogen is added to a diamond, yellow, orange and browns diamonds are created. While a combination of nitrogen and pressure results in browns, purples, pinks and reds. Usually either boron or hydrogen needs to be added to a diamond to create a blue or grey stone, whilst black diamonds are created by numerous inclusions in the diamond structure that absorb light. This gives the diamond its dark colour. Green diamonds are created through a different process and occur when diamonds have been exposed to radiation.