Natural diamonds were formed many thousands of years ago as the Earth was cooling from its volcanic cosmic beginnings as a molten planet. Intense pressure and heat at a depth of about 150 kilometers below the Earth’s surface created the diamonds we extract today: Carbon atoms that bond to three other carbons in a 2D pattern create graphite. Heat and pressure modify the atomic structure of graphite, forcing the carbons to have four bonds instead of three. The result is a much stronger 3D pattern, or, diamond.
Cool fact: Natural diamonds can also be formed by the heat and pressure of an asteroid impacting the surface of the earth.
Artificially made diamonds are grown in a laboratory from “diamond seeds”, which are extremely fine shavings cut from natural diamonds. A growth chamber provides superheated plasma and intense pressure for 28 days, at which point the “diamond seeds” grow into diamond cubes.