Nano-Polycrystalline Diamond

A completely transparent, polycrystalline synthetic consisting of randomly oriented, very tightly bonded nanoscale-sized diamond crystallites. (G&G Summer, 2012)

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 (G&G Summer, 2012)

Due to its polycrystalline nature, it is effectively uniformly hard in all directions at the macro scale and therefore requires special cutting and polishing methods - (G&G Summer, 2012)

Gems and Gemology journal (Fall 2012) pictured an 0.88 carat round brilliant stone cut from this material as an illustration accompanying the first-ever gemological characterization of NPD as a gemstone.