The existence of gem-quality synthetic diamonds and their potential impact on the marketplace has long been a source of concern to gemologists and gem dealers the world over. While we do not know whether cuttable gem-quality diamonds have been synthesized in other nations, we do know that the General Electric Company has successfully synthesized cuttable gem-quality diamonds in the United States. Eight of these diamonds were studied in an attempt to determine means of identifying them using standard gemological tests. Sophisticated chemical and X-ray diffraction analyses and spectrophotometric and ferromagnetic studies were also performed. Distinctive inclusions, absence of strain in polarized light, electrical conductivity, and absence of both an absorption spectrum and a reaction to long-wave ultraviolet radiation were found to be useful indicators. Magnetism was also found to be a positive basis for separation but is not practical for the jeweler/gemologist.