A diamond (from the ancient Greek αδάμας – adámas "unbreakable" ) is a re-arrangement of carbon atoms (those are called allotropes).

Diamonds have the highest hardness of any bulk (all one type) material. Because of this, many important industries use diamonds as tools for cutting and polishing things. Many of them are clear, but some of them have colors, like yellow, red, blue, green and pink. Diamonds of a different color are called "fancies".

Big diamonds are very rare, and are worth a lot of money. Only 20% of diamonds are fit for jewellery. The other 80% are of lower quality. Those lower quality diamonds are called industrial diamonds, and are used to make things like drill bits and diamond saws. Even if a diamond is not of gem quality, it still has a value because It is very hard.

Cut and faceted diamonds can be attractive hence their use in jewellery. Diamonds are very effective electrical insulators, but also very good conductors of heat. On Mohs scale of mineral hardness, diamonds are scored as 10 (the highest score possible).

References
"Diamond". Mindat. Retrieved July 7, 2009.
"Diamond". WebMineral. Retrieved July 7, 2009.
Carlson R.W. 2005 (22 November 2005). The mantle and core. Elsevier. p. 248. ISBN 0-08-044848-8.
Zimnisky, Paul (June 6, 2013). "A Diamond Market No Longer Controlled By De Beers". Archived from the original on 2020-10-07.