What makes diamonds shine so bright: Diamonds exhibit a high dispersion of visible light. This strong ability to split white light into its component colors is an important aspect of diamond's attraction as a gemstone, giving it impressive prismatic action that results in so-called fire in a well-cut stone. The lustre of a diamond, a characterization of how light interacts with the surface of a crystal, is brilliant and is described as adamantine, which simply means "like diamonds". This is owed to their high refractive index of 2.417 (at 589.3 nm ), which causes total internal reflection to occur. (see illustration below).

The name "diamond" derives from the ancient Greek adamas "impossible to tame". They have been treasured as gems since their use as religious icons in India at least 2,500 years ago—and usage in drill bits and engraving tools also dates to early human history. Popularity of diamonds has risen since the 19th century because of improved cutting and polishing techniques, and they are commonly judged by the "four Cs": carat, clarity, colour, and cut. Although nearly four times the mass of natural diamonds are produced as synthetic diamond each year, the vast majority of synthetic diamond production remains small, imperfect diamonds suitable only for industrial-grade use, with gem-quality synthetic diamonds only recently becoming available.

Most natural diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, Russia, Brazil, and Australia. They are generally mined from volcanic pipes, which are deep in the Earth where the high pressure and temperature enables the formation of the crystals. The mining and distribution of natural diamonds are subjects of frequent controversy, such as with concerns over the sale of conflict diamonds by African paramilitary groups. There are also allegations that the De Beers Group misuses it's dominance in the industry to control supply and manipulate price via monopolistic practices