Feature Gems & Gemology, Summer 2012, Vol. 48, No. 2

Recent Advances in CVD Synthetic Diamond Quality

Synthetic diamond growth was first documented in 1952 by William Eversole of the Union Carbide Corporation, but it took another two decades before GIA issued the first grading report for a laboratory-made diamond (Crowningshield, 1971). Virtually all single-crystal synthetic diamonds are made by two very different processes. High-pressure, high-temperature (HPHT) synthesis mimics some of the key conditions for natural diamond formation, with pressures of 5–6 GPa and temperatures of 1400–1600ºC applied to a carbonaceous source material. The second method, chemical vapor deposition (CVD), involves growing synthetic diamond as thin-film layers at moderate temperatures and low (i.e., below atmospheric) pressures. One of the main advantages of the CVD procedure over HPHT is the superior flexibility of synthetic diamond size and geometry produced. Furthermore, intentional doping with impurity elements can be controlled by the addition of gases containing those atoms.