How does carbon change into diamond?
Under extreme heat and pressure the carbon atoms squeeze together in a huge 3-dimensional network of interlocking tetrahedra which we called Diamond.
Carbon changes into diamond in the depths of the earth under high pressure and temperature. This process might have taken millions of years. Under extreme pressure and heat, the carbon atoms adopt a different bonding structure. Instead of the conventional graphite rings, the carbon atoms squeeze together in a huge 3-dimensional network of interlocking tetrahedra.
It was verified by a French scientist, Moissan with an experiment. He heated carbon and iron together in an electric furnace at 3500 degrees celsius. Carbon dissolved in the molten iron and the mass was cooled suddenly by dipping in water. Then it was put in acid. The iron dissolved and the residue was found to contain a few very small diamonds and some graphite. These results were confirmed by others too.
Today mass of diamonds are produced by this method. Artificial diamonds have similar structure, density and hardness as natural diamonds, but are very small.