Fall 2020 G&G Available Now
January 22, 2021
This issue features a unique glimpse into the overwhelming majority of diamonds submitted to GIA: those on the D-to-Z color scale. It also includes a detailed study of emeralds from Pakistan, a fascinating historical look at auctions of gems and jewels of Europe’s royal families, analysis of a rare raindrop pattern in Chinese turquoise, and a firsthand account of shell nuclei production and pearl farming in Vietnam.
Natural-Color D-to-Z Diamonds: A Crystal-Clear Perspective
The lead article, by Sally Eaton-Magaña and co-authors, examines a large dataset of colorless to near-colorless diamonds from GIA’s 2017 intake. The statistical evaluation of grading quality factors and diamond type properties has never been presented in such comprehensive detail for natural-color D-to-Z diamonds.
Inclusion and Trace Element Characteristics of Emeralds from Swat Valley, Pakistan
Hongshu Guo and coauthors provide a detailed study characterizing the various properties and chemistry of emeralds from Swat Valley, Pakistan. The researchers analyze regular and trapiche-type emeralds separately and posit that their distinct properties can be useful for geographic origin determination.
A History of European Royal Jewel Sales, Including Sotheby’s 2018 Auction of Marie Antoinette’s Jewels
Russell Shor delivers a fascinating retrospective on the accumulation of gems and jewels by the most prominent European royal houses, culminating with Sotheby’s historic Bourbon-Parma auction in 2018. This remarkable sale garnered worldwide attention as 10 lots featuring items that once belonged to Marie Antoinette faced the auction gavel.
Unique Raindrop Pattern of Turquoise from Hubei, China
Hubei Province in China produces about 70% of the turquoise available in the Chinese gem market. Hubei turquoise possessing blue and blue-green spots resembling raindrops is very popular in China and very rare. Ling Liu and coauthors use an array of spectroscopic techniques to analyze the differences in the raindrops, veins, and substrates while identifying the formation mechanism of this unique pattern in turquoise.
Vietnam: Shell Nuclei, Pearl Hatcheries, and Pearl Farming
A team from GIA’s Bangkok laboratory was granted behind-the-scenes access to two pearl farms and a shell nucleus manufacturing factory in Vietnam. In this field report, Nicholas Sturman and coauthors detail how high-quality bead nuclei are produced from raw shell and subsequently used to culture pearls on a commercial scale.
GIA laboratory staff members present their latest findings in the Lab Notes section, including “fire and ice” fluorescence in a novelty cut diamond, color-change cat’s-eye diaspore, the discovery of a 15.53 ct pearl in an edible oyster, and magnetite inclusions in star peridot.
The Micro-World section, dedicated to the inner world of gemstones, features several creatively manufactured inclusions, epigenetic residue mimicking an “egg,” a beautiful tuft of blue needles, and metal sulfide “tree” patterns, all found within their quartz hosts.
Gem News International
Finally, GNI correspondents from around the world report on bead cultured pearls embedded with near-field-communication technology, Maxixe beryl with an unusual violet color, oiled spinel, and an overview of the research presentations at the annual Geological Society of America meeting.
The Fall issue also contains the list of winners from the 2020 Gems & Gemology Challenge.
Brooke Goedert is associate editor of Gems & Gemology at GIA in Carlsbad, California.