These tool blanks consist of a layer of polycrystalline Man-Made diamond on a cemented tungsten carbide substrate, formed in to an integral blanks by high-pressure, high temperature process. The blanks thus combine the hardness and abrasion resistance of diamond with the toughness of cemented tungsten carbide. The hardness and abrasion resistance of the diamond layer are thus uniform in all directions. In contrast to single crystal mined diamonds.