Issue reveals copper-bearing liddicoatite and role of silicon in corundum
CARLSBAD, Calif. – May 10, 2017 – Colorful gems abound in GIA’s (Gemological Institute of America) quarterly professional journal Gems & Gemology (G&G). The Spring 2017 issue, now available in print and online, is the largest regular issue of G&G in its 83-year history. A diverse range of topics – from Brazilian diamonds and cuprian liddicoatite tourmaline to Japanese jadeite and the role of silicon in gem-quality corundum – are covered within the 144 pages. The first issue of the year also includes the 2016 Dr. Edward J. Gübelin Most Valuable Article Award winners and the annual G&G Challenge quiz.
The lead article, written by authors Darcy Svisero, and GIA’s James Shigley and Robert Weldon, surveys Brazil’s enigmatic diamond deposits. “Brazilian Diamonds: A Historical and Recent Perspective” recounts the history, geology and notable localities of diamond mining in Brazil. In reporting on plans for future diamond production, the article notes that although kimberlite pipes have been discovered in recent years, commercial mining will be a challenge and output remains low for now.
The second article, “Cuprian Liddicoatite Tourmaline,” by GIA researchers Yusuke Katsurada and Ziyin Sun, reports on the copper-bearing material known for its vivid blue, green and violet colors and often referred to as “Paraíba” tourmaline. Although this tourmaline is traditionally classified as elbaite species, chemical analysis identified 13 samples submitted to GIA’s Tokyo laboratory as liddicoatite. Next, an article by John L. Emmett, Yunbin Guan and GIA’s Jennifer Stone-Sundberg and Ziyin Sun discusses the critical role of silicon in the color of gem-quality corundum. The authors demonstrate that silicon’s presence is vital to allowing titanium to pair with iron and create blue color in sapphire.
The fourth article covers the history and characteristics of prized Japanese jadeite, comparing it with jadeite from other sources. Next, Xiayang Lin and Peter Heaney describe the occurrence of iridescence and differential etching in quartz crystals from India’s Jalgaon District. The Spring issue’s sixth and final article is by Ji Zhang, Yujie Gao and Guanghai Shi, investigating the properties of synthetic zincite accidentally produced by industrial kilns in Poland.
G&G’s regular Lab Notes section includes entries on rubellite with strong “pink sleeves” and intense green HPHT synthetic diamond. Gem News International highlights the Tucson gem shows, the world’s premiere colored stone event, including a new source of Ethiopian emerald and ruby and emerald mining updates. The Micro-World column features optical dishes in ametrine, flashes and flames in Ethiopian opal and cat’s-eye imitation pen pearls – as well as a mystery inclusion in topaz.
About Gia
An independent nonprofit organization, GIA (Gemological Institute of America), established in 1931, is recognized as the world’s foremost authority in gemology. GIA invented the famous 4Cs of Color, Clarity, Cut and Carat Weight in the early 1950s and in 1953, created the International Diamond Grading System™ which, today, is recognized by virtually every professional jeweler in the world.
Through research, education, gemological laboratory services, and instrument development, the Institute is dedicated to ensuring the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism. Visit www.GIA.edu.
