Abstract: Disclosed is a method of producing cubic boron nitride, which comprises the steps of subjecting to a pressure of from 40 to 70 kilobars and to a temperature of from 1100.degree. to 2000.degree. C. a charge including hexagonal boron nitride and a conversion initiator selected from the group consisting of alkali and alkaline earth metals and borides of the foregoing metals, doping the charge with crystallohydrate in the form of a compound selected from the group consisting of sulfur-, halogen- or nitrogen-containing salts and their mixtures incorporating at least 5 molecules of crystallization water. According to another embodiment, the aforesaid charge is doped with a member selected from the group consisting of alkali metal hydroxide or alkaline earth metal hydroxide.

Abstract: A method of diamond synthesis, by which a reaction mixture is prepared comprising, taken in direct contact, a carbon-containing material and a combination of components selected from the group containing silver chloride, calcium carbonate, calcium oxide and from a group containing aluminium and boron. Then the reaction mixture is subjected to the action of a temperature of at least about 1800.degree. C and a pressure corresponding to a selected temperature within the diamond stable region during the time required for forming a diamond.