PURPOSE: To improve the abrasion resistance and the diamond retention rate by preparing a compound consisting of graphite particles and a green body of carbide matrix and sintering the compound to convert the graphite into diamond.

CONSTITUTION: Graphite particles with grain diameter of 0.2-1000 μ and a green body of carbide matrix with grain diameter of 0.2-100 μ containing at least one metal carbide powder bound by a binder containing at least one elemental powder known to be diamond catalyst are blended to obtain a particle compound containing 0.5-90 vol.% of total free carbon and 0.5-50 vol.% of binder. A sintered compact containing graphite particles by sintering the green body obtained by forming the compound at a pressure of ≤30,000 psi at ≤1500°C is plated by a protection metal overcoat as required, the resulting sintered compact is introduced into an HPHT apparatus, where the sintered compact is processed under a pressure lower than 40 kbar at a temperature over 1200°C to convert the graphite into diamond.