A diamond's mineralogy begins with it's composition that is almost completely composed in carbon. It's more defining characteristics is it's hardness, toughness, tenacity, luster, and play of color. Ironically, diamonds are very hard (which is the resistance to scratching), but very brittle (it breaks, chips, cracks and can powder easily). Diamonds in rough form looks greasy but when cut and polished is possess a very strong reflective and refractive powers. It breaks up white light into rainbow spectrum and has what is known as adamantine (diamond like) luster.
Diamond also commonly possesses phosphorescence which I refer to as stored energy. Some minerals like fluorite give off light when heated or rubbed. Some diamonds give off light when it is exposed to fluoresce lighting such as blue, yellow, or even red. Alexandrite's also possess phosphorescence.
Diamonds are single refractive compared to a moissanite which is a imitation diamond and is doubly refractive and can be identified using gemological instruments.
