GIA: Gems & Gemology: Session Summaries

Geology of Gem Deposits
Studies of the geology of gem deposits are important for understanding both the gemological properties of natural gemstones and, in turn, the means of distinguishing them from treated, synthetic, and imitation gem materials. These studies investigate the dynamic geological processes that lead to the formation of rare gem materials, and the crystallization of transparent minerals that are large enough for faceting. Knowledge of their local formation conditions can be directly applied to establishing criteria for identifying the geologic or geographic origin of gems. In addition, understanding the occurrence of gem deposits within their regional or continental geologic setting can be used to predict locations to explore for new gem deposits.

Gem Characterization Techniques
Gem treatment and synthesis processes continue to advance and proliferate. In some cases, the resulting gem materials display characteristic features that can be identified by a trained gemologist using standard gem-testing equipment and techniques. However, these treated and synthetic gems may also pose significant challenges to experienced gemologists, even when using advanced nondestructive analytical techniques that are currently available. Gemologists must stay aware of new analytical techniques and take advantage of developing technology. This involves evaluating the capabilities and limitations of these new techniques for analyzing gem materials and assembling databases of information on a wide range of gem materials. In addition to improvements in instrument capabilities, technological advances are making some equipment more cost-effective for both practicing gemologists and researchers.

New Gem Localities
The growing worldwide consumer demand for attractive natural gemstones has stimulated interest in locating and exploiting new gem deposits. Future gem sources will likely include traditional gem mining areas that have not been systematically explored, as well as nontraditional areas with geologic settings that are suitable for hosting commercially significant gem occurrences. New technology is expected to aid the discovery of new deposits and can help extend the “lifetime” of existing sources. Gemologists should also stay aware of other factors that influence the development of gem sources, such as the evolution of trading centers and advances in gem treatments. Market preferences also weigh in, as seen in the demand for stones from specific localities and the growing interest in gems that do not require any treatment.

Laboratory Growth of Gem Materials
Most synthetic materials that are useful as gems are currently being produced for technological applications. The economic importance of such materials has encouraged ongoing research efforts by scientists and technicians in many countries to develop synthesis techniques and grow new and improved crystals. By staying aware of such technological advancements, gemologists may anticipate the appearance of new synthetic materials in the jewelry marketplace. A thorough characterization of new synthetic gem materials is critical so that identifying features can be publicized. The best results often come from collaborations between crystal growers and gemological researchers, as seen in recent literature on the identification of gem-quality synthetic diamonds grown by chemical vapor deposition.

General Gemology
Gemology is an evolving science, with one of its important goals being to help insure continued consumer confidence through the dissemination of information on gem materials and their identification. Developments pertaining to new gem materials, gem testing techniques, and methods of characterizing and communicating information about gem properties are important for both commercial and scientific reasons. This session will explore various areas of active research such as the relationship between optics and gem cutting, the influence of viewing environment on a gem’s appearance, the origin of color and gem phenomena, the characterization of organic materials (especially pearls), and more.

Diamond and Corundum Treatments
Diamond and corundum are two of the most important and valuable gem minerals, and there is widespread use of treatment processes to improve their color or appearance. In some cases, proper identification of these materials can only be made by the experienced staff of a well-equipped gemological laboratory (and even then may not be possible). Understanding the causes of color in diamond and corundum, and how their coloration can be changed, is paramount to identifying them correctly. Valuable information can be obtained by the systematic documentation of both known-treated and known-untreated samples, as well as by experiments that are designed to reproduce effects of treatment under various conditions.