Gem-Quality Synthetic Diamonds Grown by a Chemical Vapor Deposition (CVD) Method

Abstract

chusetts, has succeeded in growing facetable, single-crystal type IIa synthetic diamonds using a patented chemical vapor deposition (CVD) technique (Linares and Doering, 1999, 2003). For characterization of this material, the company has provided a number of brown-to-gray and near-colorless gem-quality crystals and faceted samples, which represent what is intended to become a commercial product for use in high-technology applications as well as for jewelry purposes (figure 1). Because of the growth conditions and mechanisms used, the gemological properties of these CVD-produced synthetic diamonds differ from those of both natural diamonds and synthetic diamonds grown at high pressures and temperatures. For the same reasons, the brown coloration of CVD synthetic diamonds may not react in the same way, or as efficiently, as most natural type IIa brown diamonds, which can be decolorized at high pressure and high temperature (see box A). Preliminary notes on GIA’s examination of some of these Apollo samples were published by Wang et al. (2003) and appeared in the August 8, 2003 issue of the GIA Insider (GIA’s electronic newsletter: http://www.gia.edu/newsroom/issue/2798/1842/ insider_newsletter_details.cfm#3). Spectroscopic analysis of an Apollo CVD synthetic diamond also was performed recently by other researchers (Deljanin et al., 2003). The purpose of the present article is to provide a more complete description of this material and its identifying features.