The diamond, one of the rarest materials that exist on the planet, is the only gem made of a single element: coal, in its purest form. Each diamond is the result of an extraordinary journey, from hundreds of kilometers under the surface of the earth, going through enormous pressure and very high temperatures, to become the most coveted jewel in the world.
The diamond-bearing rock, the kimbertlite, is brought close to the surface by volcanic eruptions of deep origin. The magma for such a volcano must originate at a depth where diamonds can be formed, 150 km approx. This is something that happens rarely.