Gems & Gemology Highlights Gemstone Origin and Chemistry

0
1014
The rings shown on the cover of the Spring 2019 Gems & Gemology journal feature a 15.16 ct pink cushion-cut tourmaline (left) and a 10.23 ct oval cuprian elbaite (right). The loose tourmalines (left to right) are a 75.25 ct bicolor emerald cut from Mozambique, a 4.61 ct cuprian elbaite oval from Mozambique, an 8.64 ct green oval from Namibia, a 24.60 ct pink emerald cut from Nigeria, and a 3.20 ct Paraíba tourmaline trillion from Brazil. The rings and loose stones are courtesy of Omi Privé. Photo composite by Kevin Schumacher/GIA.

Spring 2019 issue includes a gemological quiz and regular features

CARLSBAD, Calif. – May 16, 2019 – The Spring 2019 issue of Gems & Gemology (G&G) presents articles on tourmaline classification, sapphire origin determination via inclusion analysis, a legendary reliquary, identifying the origin of freshwater pearls, the impact of cut and orientation on alexandrite’s colour change and more. This latest edition of GIA’s (Gemological Institute of America’s) quarterly professional journal includes regular features – Lab Notes, Micro-World, Diamonds from the Deep and Gem News International – and announces the winners of the G&G 2018 Dr. Edward J. Gübelin Most Valuable Article Award. Readers can also test their gemological knowledge with the annual multiple-choice G&G Challenge. G&G’s Spring 2019 issue is available in print by subscription and in the GIA Store, and digitally – at no cost – on GIA.edu.

The lead article, by GIA scientists Ziyin Sun, Aaron C. Palke, Christopher M. Breeding and GIA Governor Barbara L. Dutrow, presents a simplified but comprehensive classification for tourmaline species based on quantitative measurements of six elements using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis. The second article examines the age and origin of sapphires from two Sri Lankan alluvial deposits using trace-element composition and inclusion characterization, including age-dating of zircon inclusions.

The third feature, “The Talisman of Charlemagne: New Historical and Gemological Discoveries,” gives an overview of the first scientific analysis of this ninth-century religious relic. In the fourth paper, GIA researchers use LA-ICP-MS and multivariate analysis to compare the trace-element concentrations in cultured freshwater pearls from China and the U.S. with natural pearls found in the U.S. to identify their origins.

The fifth paper, “Pleochroism and Color Change in Faceted Alexandrite: Influence of Cut and Sample Orientation,” presented by regular G&G contributor Karl Schmetzer, shows how a number of factors can impact the perceived colour of this signature colour-change form of chrysoberyl. The final article of the issue is an in-depth field report on the 2018 gemological expedition to Ethiopia, led by GIA field gemologist Wim Vertriest.

Lab Notes features the largest diamond discovered in North America, Burmese colour-change sapphire and a laboratory-grown diamond containing a CVD layer grown on a natural diamond. Diamonds from the Deep examines what we can learn from diamond age determination. Micro-World showcases the internal world of gemstones, including copper inclusions in purple chalcedony from Indonesia and a fossil insect in opal. Gem News International covers the 2019 Tucson shows with market insights and photos of beautiful and interesting specimens.

This and every issue of G&G since 1934, including full articles, lab notes, photo galleries and exclusive video footage, are available at no cost on GIA’s website at https://www.gia.edu/gems-gemology.

Additional research articles are available at http://www.gia.edu/gia-news-research.

Loading