Diamond

Diamond is an allotrope of carbon, and it is the hardest known natural material and the third-hardest known material after aggregate diamond nanorods and ultrahard fullerite. Its hardness and high dispersal of light make it useful for industrial applications and jewelry.

Diamonds are specifically famous as a material with superlative physical qualities; they make excellent abrasives because they can be injured only by other diamonds, Borazon, ultrahard fullerite, or aggregated diamond nanorods, which also means they hold a polish tremendously well and retain their luster. Approximately 130 million carats (26,000 kg) are mined annually, with a sum value of nearly USD $9 billion, and about 100,000 kg (220,000 lb) are synthesize annually.