Process for synthesizing diamond

1,138,410. Synthetic diamond. E. I. DU PONT DE NEMOURS & CO. 20 Nov., 1967 [21 Nov., 1966], No. 52768/67. Addition to 1,115,648. Heading C1A. A process for preparing diamond by an explosive shock synthesis method using a cooling medium according to a synthesis process claimed in Specification 1,115,648, with the modification that instead of using graphite, intimately mixed with the cooling medium, as starting material, another form of non-diamond carbon is used. The carbon, which preferably constitutes no more than about 85% by volume of the mixture, especially no more than 65% of the mixture with more porous cooling media, is heated to drive off volatile impurities before subjection to the explosive shock-synthesis process. Carbons referred to are carbon black e.g. acetylene black, charcoal (bone or wood char), coke and completely carburized polyacrylonitrile yarn.