Did You Know? – Coloured Diamonds

When it comes to diamonds, the first thing people might think of is a clear gemstone with no perceivable colour. This definitely is a perfect diamond's representations, but the fact of the matter is that these are very, very rare. What many people do not realise is that there are different colours of diamonds – nearly every colour in the rainbow.

A one-carat diamond needs billions of carbon atoms to bond to create a colourless stone and yet the smallest element inclusion creates a coloured diamond.


Red is the rarest colour among diamonds and the most expensive. This colour is said to be caused by changes to the electron structure during a diamond’s quest to the surface.


Orange diamonds bear structural irregularities in combination with trace amounts of nitrogen. However, the exact cause of this colour is still being studied.


Yellow diamonds are very common and some of the most brilliant yellow-coloured diamonds are mined in South Africa. They become yellow due to nitrogen.


Green diamonds are also rare, with less than ten green diamonds turning up on the market every year. The colouring in most greens is due to nickel mixed with carbon. Natural radiation from nearby rocks, which traps electrons, creates a green surface colour.


Blue diamonds are also found in South Africa, and they owe their colouring to boron with a low level of nitrogen. Some blue diamonds have nothing to do with boron; wherein nickel or highly-concentrated hydrogen are the theoretical causes of blue colour.


Purple is the third rarest colour among diamonds. Many scientists believe that they are formed due to post-growth plastic deformation while travelling from the earth’s mantle to its surface through magma.


Pink diamond’s colouring is due to alterations of electron structure, called “plastic deformation,” throughout their quest to the surface. Most pink diamonds were mined in Australia which makes for about 90% of natural pink diamonds across the globe.


Grey diamonds encompass boron in their carbon structures, or high amounts of hydrogen.


Brown diamonds are predominantly found in Africa, Australia and Siberia. They include nitrogen. The lighter brown stones are known as “champagne diamond” while the darker ones are “cognac diamond.”


Black diamonds are not related to any elements. They do have small inclusions of iron and graphite providing for that black colouring. However, they are not necessarily black as they may have clear white or grey tints. If you seek to enhance its colour, consider high-pressure, high-temperature treatment (HPHT), dyeing a diamond or irradiation.