Our cover article, by Nathan Renfro, analytical manager of the gem identification department at GIA’s Carlsbad laboratory, focuses on digital photomicrography for gemologists. Renfro’s article builds on the landmark 2003 paper by his longtime mentor and master of gem-inclusion photography John Koivula, to offer a highly practical and relevant guide covering equipment and current techniques for the gemologist.
In the lead article, we present a paper by a team of researchers headed by Dr. Karl Schmetzer, a frequent contributor to Gems & Gemology during the 1980s and 1990s. We are delighted to welcome Dr. Schmetzer back to our journal. He and his coauthors offer a comprehensive description of a largely unappreciated form of asterism: the dual-color “double stars” observed in some natural sapphire, ruby, and quartz, as well as synthetic corundum, including diffusion-treated examples. The authors discuss the mechanism by which double stars are formed and present a historical summary of the manufacture and improvement of synthetic star corundum by diffusion treatment.
Our third article, by Russian researcher Dr. Elena Sorokina and her coauthors, provides an update on the geology, mining, and internal and external features of ruby and sapphire from Snezhnoe, Tajikistan. This is a welcome summary of a marble-hosted deposit with significant potential, one that has seen little study or previous coverage in the gemological literature.We invite gemologists to take a closer look at the astounding beauty and variety of the micro-world of gems.
After these three feature articles, you’ll find our regular Lab Notes and Gem News International sections, which include further entries from the 2015 Tucson shows and a report of the recent Maine pegmatite workshop.
In addition, we present a new quarterly column on inclusions entitled “Micro-World.” With this new regular feature, section editors Nathan Renfro, Elise Skalwold, and John Koivula aim to foster the wider appreciation of inclusions and to bolster practicing gemologists’ observational skills by providing concise reports accompanied by stunning photomicrographs of specially chosen specimens. The authors invite gemologists to take a closer look at the astounding beauty and variety of inclusions in gems.
Finally, I'd like to thank Stuart and the entire G&G editorial and production staff. Due to the unexpected death of a close family member, I have been out of the United States for a period of weeks. As a result, I have come to appreciate the hard work and dedication of the entire G&G team even more.
All of us at G&G hope you enjoy the Summer issue!