CVD-Grown Synthetic Diamonds, Part 1: History
2020-2-22 · To produce a gem-quality synthetic diamond, a diamond seed crystal (natural, HPHT, or CVD in origin) is introduced into the gas mixture, at an elevated temperature of 900 to 1200°C. The activated carbon-hydrogen species travels across the surface of the diamond seed until it finds an available carbon atom, and then attaches itself to this seed