Interest in the synthesis of diamonds was first stimulated by Lavoisier's discovery that diamond was simply carbon. In the attempt at diamond synthesis, much unsuccessful effort was devoted to processes that deposited carbon at low, graphite stable pressure. New high pressure apparatus was built, rebuilt, and sometimes discarded. Months after operating pressures of 7GPa had been attained, a reproducible diamond synthesis was finally achieved. The two major innovations in diamond technology are the reproducible high temperature‐high pressure process with metal solvent/catalyst and the low pressure sustained growth from methane‐hydrogen (CVD). Direct graphite to diamond processes are also discussed. Synthetic diamonds are used as gemstones. CVD processes have been used to produce single crystal diamonds. Synthetic diamonds have many industrial uses: as grit and powder in diamond grinding wheels, saws, polishing, thermal management, electronic applications and electrochemical uses. Polycrystalline diamonds are also discussed.