Cutter for a rotary drill bit, rotary drill bit with such a cutter, and method of manufacturing such a cutter

A cutter, for use in a rotary drill bit, comprises a number of thermally stable polycrystalline diamond elements 21 at least partly embedded in a slug 20 of cemented tungsten carbide, the cemented tungsten carbide having been formed by hot pressing with cobalt. The thermally stable polycrystalline diamond may be of the kind in which the interstices between the diamond particles are substantially filled with silicon carbide, or of the kind in which metallic interstitial components have been leached out, and each element has been coated with a protective material, such as nickel.