Articles and News

Carlsbad, CA—The Spring 2021 issue of GIA’s Gems & Gemology (G&G) is packed with research insights and interviews with leaders in the trade about how their businesses weathered the turbulent past year. G&G is GIA’s quarterly science journal dedicated to all things gemological. Cover image: The internal structures of natural pearls from the marine mollusk Pinctada maxima are the subject of the lead article in this issue. The scattered loose pearls on the cover are from Paspaley’s natural pearl collection, which includes one discovered in the 1970s at the Eighty Mile Beach fishing grounds. Courtesy of Paspaley Pearls Pty Ltd.

Here are the featured articles in the spring issue:

• Internal Structures of Known Pinctada maxima Pearls: Natural Pearls from Wild Mollusks, by Artitaya Homkrajae, Areeya Manustrong, Nanthaporn Nilpetploy, Nicholas Sturman, Kwanreun Lawanwong, and Promlikit Kessrapong, presents the internal characteristics of natural P. maxima pearls, obtained from real-time microradiography (RTX) and X-ray computed microtomography (μ-CT) analysis of 774 samples.
• Technical Evolution and Identification of Resin-Filled Turquoise, by Ling Liu, Mingxing Yang, Yan Li, Jingru Di, Ruoxi Chen, Jia Liu, and Chong He, provides criteria for detecting the resin filling of turquoise, an advanced treatment that reduces porosity and can dramatically improve appearance and stability.
• How to Calculate Color from Spectra of Uniaxial Gemstones, by Che Shen, Aaron Palke, Ziyin Sun, and Mark D. Fairchild, presents a method for accurately predicting the color of a gem material when viewed in any direction as long as the polarized spectra and the viewing angle relative to the c-axis are known.
• Micro-Features of Spinel, by Nathan Renfro, John I. Koivula, Shane F. McClure, Kevin Schumacher, and James E. Shigley, accompanies a wall chart—enclosed with every printed copy of this issue—that shows the internal features of natural, synthetic, and treated spinel, as well as inclusions of spinel in other gemstones.

G&G’s regular features continue to highlight interesting gemological findings from around the world. In Lab Notes, discover bicolor rough diamond crystals, asterism in natural diamond cabochons, a green opal displaying aventurescence, a lead glass-filled laboratory-grown ruby and more. G&G Micro-World zooms in on a plethora of internal features in colored stones, as well as a diamond surface that expanded due to radiation staining and other unique finds.

Gem News International offers a virtual report on the gem industry in 2021, the Chinese gem and jewelry industry’s reaction to COVID and other important topics, and the Dr. Edward J. Gübelin Most Valuable Article Award.

Gemologists and gem enthusiasts can test their knowledge of G&G articles from 2020 by taking the G&G Challenge, a multiple-choice quiz on the journal’s articles, available here.

Every issue of G&G since 1934 is available at no cost on GIA’s website at GIA.edu/gems-gemology. Additional research articles are available at GIA.edu/gia-news-research. Stay up to date and engage in gemology conversations with an online community of nearly 16,000 members in the GIA Gems & Gemology Facebook group: facebook.com/groups/giagemsgemology.