Preface
by Dr. James Shigley

The 1970 announcement by General Electric Co. (GE) of the creation of one-carat gem-quality synthetic diamonds was hailed as another major scientific breakthrough, but it was met with some alarm by members of the jewelry industry. Despite claims to the contrary by GE management, jewelers were concerned about the possible manufacture of inexpensive gem-quality synthetic diamonds that might be difficult or impossible to distinguish from natural gem diamonds. Shortly after the GE announcement, GIA’s widely recognized gem expert G. Robert Crowningshield examined a selection of these new synthetic diamonds and subsequently described some practical gemological means by which jewelers could identify them (Crowningshield, 1970 and 1971).

The early work carried out by Crowningshield initiated an investigation of synthetic diamonds and their means of identification that has continued at GIA for more than three decades. As new products have been developed in Japan, Russia, and elsewhere, concerns regarding the widespread availability of synthetic diamonds and the challenge of their recognition have persisted among jewelers. To address these concerns, gemological researchers worldwide have studied laboratory-grown diamonds from all known sources of experimental and commercial production. This work has established means of recognizing them by standard gem-testing procedures and equipment, as well as by advanced testing methods not always available in gemological laboratories. These means of identification have been widely publicized in gemological journals and jewelry trade publications, in presentations to industry audiences, and in educational materials. Much of this information appeared in print for the first time in Gems & Gemology.

The gemological importance of synthetic diamonds, and the sustained and significant research effort that has been directed at them over the past 35 years, warrants this special GIA publication, the first of a series, which brings together the numerous articles and other information on the subject published in Gems & Gemology since Crowningshield’s 1971 article on GE’s “Cuttable Synthetic Diamonds.” Besides individual articles, this collection includes selected entries from both the Lab Notes and Gem News (renamed Gem News International in 2001) sections of the journal, relevant editorials, and reports presented at GIA’s 1991 and 1999 International Gemological Symposia. While other authors have published occasionally on laboratory-created diamonds in gemological books and journals, there is no similar compilation of the original articles on this subject. The fact that many past issues of Gems & Gemology are no longer in print is another reason to provide this information on synthetic diamonds in a single volume.

For the most part, the original publications included in this monograph are presented in chronological order. This allows the reader to follow the growing understanding of synthetic diamond identification among gemological researchers. Because some individuals participated in a number of these publications, the information in “About the Authors” has been consolidated and presented at the end of the text pages. Likewise, to preclude the repeated citation of the same articles in multiple reference lists, a single consolidated bibliography contains all references cited in the original publications as well as in the new editorial material in this volume. This consolidated list also contains two sections titled “Suggested Additional Reading”—references in the literature that were not cited in the original Gems & Gemology articles, but nonetheless are useful sources of additional information on both HPHT- and CVD-grown synthetic diamonds. In many cases, the original entries have been reformatted and illustrations have been modified to fit the style of this volume. There also has been minor copyediting for stylistic consistency, such as the abbreviation “GE” (rather than “G.E.”) throughout. However, affiliations in the “Acknowledgments” have been left as they were originally published.

For purposes of organization and discussion, the original articles and other items are grouped here into five parts:

1.         First reports on synthetic diamonds

2.         Early synthetic diamonds in the jewelry trade

3.         Advances in manufacture and identification

4.         HPHT-grown synthetic diamonds in the 21st century

5.         CVD-grown synthetic diamonds

Each section is preceded by an introductory essay that places the material in the context of subsequent developments and the current status of synthetic diamond manufacturing and identification. In addition to the original articles with which they appeared, two full-size wall charts are provided at the end of the volume. The first is the one published by Shigley et al. (1995), which compares the properties (and identifying features) of natural and HPHT-grown synthetic yellow, blue, and colorless to near-colorless diamonds examined as of the mid-1990s. The second, which was published by Shigley et al. in 2004, presents the characteristics of as-grown and treated HPHT synthetic diamonds currently in the gem market.

As laboratory-created diamonds become more common in the jewelry industry, jewelers and gemologists need to know what they might encounter, and must be more vigilant in learning how they can be identified. This volume not only traces the development of gem-quality synthetic diamonds, but it also provides the interested reader with a better understanding of their key distinguishing features.

James E. Shigley
Editor