Nano-Polycrystalline Diamond

A variety of Diamond

Nano-Polycrystalline Diamond (or NPD) is a completely transparent, polycrystalline synthetic consisting of randomly oriented, very tightly bonded nanoscale-sized diamond crystallites.

Using a sintering process, the material is created in a multi-anvil press at 15 gigapascals (2.18 million psi) and 2,300 to 2,500°C. High-purity graphite is thus converted directly into cubic diamond in a matter of minutes. The resulting NPD is composed of a mixture of 10-20 nm equigranular crystallites and 30-100 nm lamellar crystalline structures. It is harder and tougher than natural diamond and can be fashioned into a variety of shapes using lasers, even a perfect sphere - a shape which would be virtually impossible using single crystal diamond. (see G&G Summer 2012)

In 2015 it was reported that naturally occurring NPD was found at the Popigai impact crater in Russia.