Spring 2020 G&G Available Now
July 22, 2020
After being delayed by the global pandemic, the Spring 2020 edition of Gems & Gemology is available now. This issue features two articles that quantitatively analyze the causes of color in corundum and blue to yellow beryl, respectively, with a focus on chromophores. It also offers an exciting look back at the evolution of jade carving craftsmanship in China, the rediscovery and early production of the Chivor emerald mine, an analysis of Swiss rhodonite, coverage of the Tuscon gem shows, and more.
A Quantitative Description of the Causes of Color in Corundum
The lead article, by Emily Dubinsky and co-authors, investigates the quantitative relationship between corundum’s color and chemistry. Using quantitative visible absorption spectroscopy and chemical analysis by SIMS, the authors are able to calculate the absorption cross section of six major chromophores that cause a wide array of color in corundum. Data is presented in the form of spectra and color circles.
The Evolution of Chinese Jade Carving Craftsmanship
China’s oldest and most important art form, jade carving, is steeped in history going back thousands of years. Mingying Wang and Guanghai Shi explore the evolution of jade carving tools and their impact on carving craftsmanship. With advancements in technology, jade carving has increased in complexity and delicacy while still reflecting Chinese philosophy and culture.
Color Characteristics of Blue to Yellow Beryl from Multiple Origins
Yang Hu and Ren Lu use quantitative spectroscopy and trace-element analytical techniques to study color characteristics and chromophores in blue to yellow beryl. This article also discusses the complex roles alkali ions and water have in beryl, though their influence on the blue to yellow color was found to be indirect.
History of the Chivor Emerald Mine, Part I (1880-1925): From Rediscovery to Early Production
Karl Schmetzer and co-authors dig deep into the history of the Chivor emerald mine in the first part of a two-part article. Their extensive research seeks to clarify historical inconsistencies, starting with the rediscovery of the site by Colombian mining engineer Francisco Restrepo, to mining title transfers and mining company formations, the impact of World War I, and the eventual bankruptcy of the Colombian Emerald Syndicate, Ltd.
Rhodonite-Pyroxmangite from Tanatz Alp, Switzerland
Swiss rhodonite is typically used to make cabochons, beads, and ornamental objects. Franca Caucia and co-authors analyze the chemical, physical, and gemological properties of this pale pink to purplish pink material. Rhodonite deposits can be found all over the world and have been widely investigated, but material from the Tanatz Alp is less well known.
GIA laboratory staff members present their latest findings in the Lab Notes section, including the “Matryoshka” diamond from Siberia, corundum inclusions in diamond, an “electronic device” in an atypical bead cultured pearl, and the use of fluorescence spectroscopy for colored pearl treatment screening.
The Micro-World section, dedicated to the inner world of gemstones, features reversible twinning in neodymium pentaphosphate, a pallasitic peridot with iridescent needles, and sapphire with a phenomenon resembling play-of-color.
Diamonds from the Deep
Karen Smit and Steven Shirey examine the dissolution features that occur on diamond during storage in the mantle and transport to the earth’s surface. These unique surface features, influenced by the composition and temperature of the dissolving fluid/melt, help scientists better understand when diamond grows or dissolves.
Gem News International
Finally, GNI correspondents from around the world report on the Tucson 2020 gem shows, sapphires from Montana and Australia, sunstone from Ethiopia, and the new mineral dutrowite, named after well-known researcher, professor, and GIA governor Barbara Dutrow.
The Spring issue also contains the 2020 Gems & Gemology Challenge. Score 75% or better and you’ll receive a certificate of completion (PDF file); earn a perfect score and your name will be listed in the Fall 2020 issue. Online entries for the Challenge must be submitted by Friday, October 9, 2020.
Brooke Goedert is associate editor of Gems & Gemology at GIA in Carlsbad, California.