Natural diamonds and their cuts

Natural diamonds and their cuts

Written by Holly Chilcott on 29 March 2016

Everybody knows what a diamond is, it’s that beautiful clear stone that traditionally sits in an engagement ring. But if you were asked, would you actually know where a diamond comes from or how it was formed?

Geologists believe that diamond deposits were formed in mantle deep beneath the earth’s surface and brought up to the surface by deep source volcanic eruptions. Down in the mantle the pressure and temperatures reaching 1500 Celsius change the molecular structure of carbon by crushing its atoms together and forcing them into a new lattice like structure which creates diamonds. They are transported to the surface with a substance called Kimberlite which is a volcanic rock that forms deep within the earth. As it moves to the surface it creates a pipe filled with molten rock, mantle fragments and diamonds. When it breaks through the earth’s crust it erupts in small but violent volcanoes. The magma from the volcano cools and hardens and hidden within this rock are diamonds, ready to be mined.

It is thought as well that diamonds can even come from outer space! It’s not as crazy as it sounds, in 2008 a meteorite exploded over the Nubian Desert in Sudan. The rock fragments actually contained diamonds which were much larger than seen before in a meteorite. Scientists believe that large diamonds like this are most likely to form inside a lump of rock the size of a planet. So these diamonds could be from a planet that existed when our solar system was forming and has seen been shattered.

Diamond rough stones come in different shapes and the most preferred shape is an octahedron. The shape looks like two pyramids put together creating that classic diamond silhouette. The octahedron lends itself to being cut into two princess or brilliant cut diamonds making it very economical with very little waste. In fact the cut of a diamond, whether it’s brilliant, pear or cushion cut, is completely dependent on the shape of the natural crystal. Scanning devises are used to get a 3D computer model of the rough stone and inclusions are photographed which is then used to find an optimal way to cut the stone.

This makes some cuts of diamond harder or more expensive to source for your bespoke jewellery as there may not be enough rough stones suitable for the cut that you want, on the market!