Diamonds are a naturally occurring mineral, one of two crystalline forms of the element Carbon.
Chemically, diamonds are pure carbon crystals, and each carbon atom is held tightly by four bonds to other carbon atoms nearby. Diamonds are the hardest naturally occurring substance known because of the strength of these bonds. Silicon carbine relies on carbon bonds as well for its strength. Silicon carbide is the third hardest compound known to mankind. Moissanite is created with silicon and carbon, through a combination of pressure and heat.