The connection between kimberlite pipes and diamonds.

It's been discovered, that diamonds are brought close to the surface of the earth through volcanic eruptions which are originated in the depth of the earth, carrying diamond-bearing rocks through volcanic pipes.

The kimberlite is an igneous diamond-bearing rock, which is formed and solidifies after the molten magma is cooled. The magma itself does not contain diamonds, but acts as an elevator that carries, among other materials, rocks, fluids and minerals upward. The kimberlite material is full of large spaces, occupied by the diamonds. During a volcanic eruption these pipes are open to the surface, lifting the kimberlite closer to the surface.

The magma for such volcanic eruptions must originate at a depth where diamonds can be formed, which is three times than source magma for most volcanoes, or even deeper.

The diamond, as mentioned before, is a crystal compounded almost entirely of carbon atoms. Transformation of carbon-bearing minerals into natural diamond requires existence of two very specific conditions:

a. Extreme pressure ranging approximately between 45 and 60 kilobars.

b. The temperature must be of approximately 1200-1600 Celsius degrees.

These conditions are known to be met in the depth of the earth (between 140–190 kilometers, sometimes even 300-400 km. less than that – if carbon is present – formation of a graphite mineral will occur).

When the conditions which are necessary for the diamond to crystallize in the molten mass occur, the carbon atoms start to move through the fluid, each encounter between them leads to an attachment, which creates the basic form of the diamond. The atoms keeps moving, accumulating more and more atoms, creating the structure of the diamond.

As mentioned before – each carbon atom is linked to four other atoms by 4 valence electrons (sketch 1). When individual atoms join the crystal, they will merge in the orderly manner of a diamond structure. A large group of atoms however, might join the crystal in a way that could leave gaps in the diamond's structure, or even resolve in a twisted structure, given the different formation periods.

Conclusion:

Although there is still no conclusive theory with regards to diamonds formation, there's one definite conclusion which is – that diamonds are formed in the depth of the earth, deeper than any other gemstone.

It appears that diamonds were formed out of carbon, through long periods of time, in dissolved magma pools in the crust of the earth. It is probable that the magma in its plastic status had been pressured upward by gasses exploding from a very low depth, and in that motion the lava had punctured the earth’s crust with a relatively small number of pipes which had eventually cooled and hardened. The magma, on its way to the earth’s crust had gone through a chemical transformation. In that process many rocks and minerals had been added to it, resulting in the creation of the kimberlite, which carries inside it one of the most magnificent creations of nature – the diamond.