Diamond which is the most crystalline form of carbon is obtained from mines. At900 degree C, it starts burning slowly and combines with atmospheric oxygen to form carbon dioxide. At 1000 degree C. It gets converted into graphite. At higher temperatures the rate of formation of graphite is faster. It is a good conductor of heat but bad conductor of electricity. Its thermal conductivity is five times greater than that of copper.

Until 1995, diamond was obtained only form mines but later certain synthetic methods for its manufacture were also developed. Diamond obtained from mines is called natural diamond, whereas the one made by synthetic methods is called artificial diamond. Africa is the biggest source of natural diamonds. About 95%of these come from this continent. Before they come to he market for sale, they are cut into different shapes and polished. The shine of diamonds is not spoiled even after hundreds of years. Synthetic diamonds were made for the first time in the world by the general electric Co. of USA in 1955. in the synthetic process, diamonds are produced from graphite. In high temperature furnaces graphite is heated to about 3000 degree C under high pressure. By doing so graphite is converted into diamond. Synthetic diamond resembles the natural diamond in many respects. These are generally used in jeweler and industry.