Non-destructive residual stress investigations of natural polycrystalline diamonds

Three natural polycrystalline diamond samples have been investigated non-destructively in their raw as-discovered forms. The samples originate from different locations in the world and possibly have different mechanisms of formation. The study reveals that the stones are primarily composed of cubic diamond with varying amounts of impurities that emanate from their excessive porosities and entrapped environmental contamination, contributed by the areas in which they were formed and subsequently discovered. Residual stress analyses of the cubic diamond phase with Xray and neutron diffraction techniques revealed low stress values in the interior regions of the diamonds.