The micro-world of gems lies at the very core of gemology. Sometimes its nature contributes to the allure of a gem, as is the case with such coveted gems as sunstones, star sapphires, and cat’s-eye chrysoberyls. At other times that world may seem a dreadful distraction to an otherwise beautiful, marketable specimen. But even in what appears to be a perfectly clean gem, this micro-world waits for gemologists to dive into its depths and thoroughly explore its landscape. The visitor will be greeted with a beautiful and wondrous inner space, and the unexpected secrets revealed will come to enrich one’s understanding of gem materials in innumerable ways.
While hints of the internal features may be glimpsed with the loupe or the unaided eye, true access is afforded by the microscope. This is unequivocally the most important instrument in the gemologist’s arsenal once its proper use is mastered, particularly with the application of special lighting techniques and the use of various filters (see N. Renfro, “Digital photomicrography for gemologists” in the current issue, as well as J. I. Koivula, “Photomicrography for gemologists,” Spring 2003 G&G, pp. 4–23).
For newcomers, an understanding of the micro-world may seem elusive, even daunting. Continual practice, careful observation, and patience will refine both technique and interpretive prowess for both new and experienced inclusionists. Observation through the microscope serves as the very foundation for many conclusions drawn on a specimen. This can include identification, treatment detection, separation of natural and synthetic materials, and geographic origin—even secrets of a gem’s genesis and the secrets of the earth’s depths may ultimately be revealed.
In building proficiency of the micro-world through this column, readers will also expand their personal knowledge base and ability with a microscope. Mastery of microscopy, combined with at least a basic grasp of mineralogy, is essential for understanding the nature of gems and the geologic processes that occur within the earth. This increased knowledge will eventually translate into a better comprehension of the inclusion scenes that may be encountered in one’s own micro-world.
With this column, we hope to inspire gemologists to simply take the time for a closer look. We invite you to join us for an extended tour through the astounding beauty and variety that is the micro-world of gems and other related materials.
Elise A. Skalwold, an Accredited Senior Gemologist of the Accredited Gemologists Association (AGA), is involved in curating and research at her alma mater, Cornell University. A Graduate Gemologist and Diploma Merit graduate of the Gemmological Association of Great Britain, she has written gemological and mineralogy-related articles, as well as the book The Edward Arthur Metzger Gem Collection. Her primary interests are inclusions, crystallography, and optical mineralogy.
Nathan Renfro is the analytical manager of the gem identification department and analytical microscopist in the inclusion research department at GIA in Carlsbad, California. Mr. Renfro holds a degree in geology and a Graduate Gemologist diploma (GIA) and is a Fellow of the Gemmological Association of Great Britain (FGA). He has authored and co-authored numerous gemological articles and has particular interests in inclusion identification and lapidary arts.
John I. Koivula is the analytical microscopist at GIA and a Fellow of the Royal Microscopical Society. A mineralogist, chemist, and gemologist with more than 40 years of experience, he is a world-renowned inclusion expert and photomicrographer. In addition to hundreds of articles and peer-reviewed scientific papers, Mr. Koivula is author of The MicroWorld of Diamonds and co-author of the three-volume Photoatlas of Inclusions in Gemstones, which features over 5,000 of his unique photomicrographs.