Article - Every Colour of the Spectrum - Coloured Diamonds

Article - Every Colour of the Spectrum - Coloured Diamonds

Written by Sarah Dilley on 9 February 2015

Most naturally formed diamonds are colourless to a light yellow colour and this is what we see most of in our engagement rings, but some have a natural more vivid colour and these are known as fancy colour diamonds.

This article is going to briefly discuss natural coloured diamonds, focusing on new research exploring natural pink diamonds.

Fancy Diamonds

Fancy diamonds are valued on their intensity of their colour. Roughly for every one diamond that is found with colour there are ten thousand white diamonds toned diamonds. Diamonds can be found in a variety of natural colours, yellow and brown diamonds are the found more than any other colour of diamond. Whereas, blue and red diamonds being the rarest and hardest to find.

The colour diamonds are often found in the same mine as colourless diamonds, so what causes the some diamonds to be coloured and others to be colourless?

Diamonds are very pure carbon that is crystallised more than one hundred kilometres below the Earth’s surface. They grow underneath the surface, in extremely high temperatures, just like colourless diamonds; they are then transported to the surface, normally through volcanic activity. Other atoms can become trapped in the diamonds as it grows or during its journey to the surface. It is these atoms that can create colour. For example Nitrogen, and even the very smallest amount causes blue to be absorbed within the diamonds crystal structure meaning it has a yellow appearance.

Pink Diamonds

The Argyle mine in Australia is a phenomenon in itself been the source of very rare pink diamonds. The mine itself was established in 1983 and was the first major diamond mine in Australia. It has been known to be home to a very limited amount of rare pink diamonds. This mine is actually one of the world’s largest producers of diamonds in terms of volume. The mine is slowly coming to the end of its life, with having fifty fine coloured diamonds found each year. It is thought that the mine will be closed within the next five years, as there will be little left to find.

Bizarrely although natural pink diamonds are one of the world rarest gemstones, nobody actually knows from certain what causes them to be pink! Scientist’s are currently studying the pink diamonds that are found in the Argyle mine and the site itself in a hope to find the answers. They are using a really fancy piece of kit called a mass spectrometer, which hopes to be able to find any traces of impurities as well as looking at the structure of the pink diamond itself.

They have also cut a trench in the surface of the diamond, using an ion beam, where they have removed different elements to measure under really powerful electron microscopes. They now know that these diamonds are not the same pink all the way through, they have pinks zones and clear areas. These different zones are knows as twin planes. These planes are believed to be created by a shock, which could be from the volcanic activity that a diamond finds its self facing with through the process of being created. Although the scientists currently think that it is not this twin plane that causes the colour, but the movement between the two planes could maybe cause a defect in the diamond causing it to turn pink.

As little as twenty years ago pink diamonds were only of interest to gemmologists but they are now one of the most valuable gemstones in the world today. A pink diamonds beauty and rarity make it a sought after gemstone. In 2013 Sotheby’s auctioned a pink diamond. It was an amazingly large 59.6ct oval pink diamond in Hong Know that fetched an astonishing £11.07million.It really is no wonder that we are seeing more and more customers choosing pink gemstones for their precious pieces of jewellery.