Diamonds are not formed in the Earth's crust as most other gemstones are. They are formed by great heat and extreme pressure, much deeper down in the layer of volcanic magma called the mantle. Temperatures here reach 1000 degrees centigrade and the pressure can be as high as 50 kilobars - 50 times more pressure than you would be put under if it was possible to dive to the deepest point in an ocean.

The earth's mantle is very large so there is the possibility that within it is billions of forming diamonds awaiting a time when they are exploded on to the earths surface. It is simply a random event that sends these beautiful gems to the surface. They are expelled through “Kimerlite Pipes” when an underground explosion pushes magma at huge speed through one of these pipes taking with it one or more diamonds.

These fabulous stones are found in rivers, plains or seas. As such they are alluvial, as are sapphires and rubies and because of the nature of their expulsion from the mantle causing them to be found in river beds it is very difficult to say exactly where a particular diamond originates from. Often they have travelled for thousands of miles from their origin.

They are graphite, a rare transparent form of pure carbon made from the same elements as ordinary coal. They are 10th on Moths scale of relative hardness with talc being no 1, So hard they can only be scratched or cut by another diamond.

Depending on the trace mineral found where they are formed their colour may vary from blues to yellows. They are very popular still for all types of jewellery and were used in engagements as far back as the late 15 century. They are the birth stone for those born in April and depending on which list you follow, the old or modern, they are especially used for the 10th, 30th and or 60th wedding anniversaries.