Diamond is a pure or nearly pure, extremely hard form of carbon, naturally crystallized in the
isometric system. Diamonds can be identified by their high thermal conductivity. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms.
                     The first recorded history of the diamond dates back some 3,000 years to India, where it is
likely that diamonds were first valued for their ability to refract light. In those days, the diamond was used in two ways-for decorative purposes, and as a talisman to ward off evil or provide protection in battle.
                     Diamonds are an ideal of mechanical parts that resist wear and undergo a sudden temperature
changes and that not change size, create friction or rust. Diamond bearing are used in instruments for laboratories. No friction is created when rubbing them together because of their hardness. Some machines turn at 90 000 revolutions a minute. No lubrications are needed even at this high speed to keep the bearing from wearing away. Diamond cutting tools cut much faster and accurately than other tools. Metals can be sliced thinner than human hair by the diamond blade.
                      A large trade in gem-grade diamonds exists. Unlike other commodities, such as most precious
metals, there is a substantial mark-up in the retail sale of gem diamonds. There is a well- established market for resale of polished diamonds (e.g. pawn broking, auctions, second-hand jewelry stores, diamantaires, bourses, etc.). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to just a few locations; in 2003, 92% of the world's diamonds were cut and polished in Surat, India. Other important centers of diamond cutting and trading are the Antwerp diamond district in Belgium, where the International Gemological Institute is based, London, the Diamond District in New York City, Tel Aviv, and Amsterdam.

A Diamond


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