A polycrystalline diamond body whose surface is free of group VIII metals

A polycrystalline diamond body 57 has a top surface 52 and a side surface 58. The body is made from bonded diamond crystals. The body is attached to a metallic substrate 60. There is a region 56 where the gaps between the crystals are free of a group VIII metal. There is another region where the gaps between the crystals contain a group VIII metal. The region free of the metal may extend over various sections of the top and side surfaces of the body; it may be in the region of 0.04-0.08mm deep. The separate regions can be formed by treating only a portion of a body whose gaps initially all contain the metal. Leaching is one such treatment. The group VIII transition metal could be a catalyst for sintering the diamond crystals.