Fall 2021 G&G Available Now
November 30, 2021
The Fall issue presents the second article in a three-part series on Pinctada maxima with a detailed documentation of the internal structures of cultured pearls. The next two articles present unique findings: the first identification of sudoite in as a lapidary material and the first reported example of specific chromophores causing a purple color in spinel. Lastly, a field report highlights the current state of mining and production at Neyshabur, Iran’s largest turquoise mine.
Internal Structures of Known Pinctada maxima Pearls: Cultured Pearls from Operated Marine Mollusks
The lead article, by Artitaya Homkrajae and co-authors, studies the internal structures of 74 non-bead cultured (NBC) and 12 bead cultured (BC) pearls harvested directly from farmed mollusks off the coast of Western Australia. Characteristic internal features of most NBC samples allowed separation from their natural counterparts, with a few exceptions that proved challenging and could result in an inconclusive call in a laboratory.
First Identification of Sudoite in Caribbean Ceramic-Age Lapidary Craftsmanship
A research team led by Alain Queffelec examines nine sudoite artifacts from several archaeological sites in the French West Indies. This material was previously unknown in sizes large enough for carving and has never before been identified in lapidary craft.
Purple Gem Spinel from Vietnam and Afghanistan: Comparison of Trace Element Chemistry, Cause of Color, and Inclusions
Philippe Belley and Aaron Palke investigate the chromophore combinations responsible for the purple coloration in two spinel samples from Vietnam and Afghanistan. This article presents the first reported example of chromium and cobalt causing the saturated purple color in a gem spinel.
Persian Turquoise: The Ancient Treasure of Neyshabur
This field report by Bahareh Shirdam and co-authors describes the current state of the Neyshabur turquoise mine, located in northeastern Iran. The authors highlight the local geology, mining techniques, and turquoise production from mine to market.
GIA laboratory staff members present their latest findings in the Lab Notes section, including multiple fossilized shells composed primarily of emerald, a parcel of manufactured glass masquerading as blue star sapphire, and a batch of large CVD-grown diamonds with high clarity and color for as-grown material, which offers insight into potential new growth conditions.
The Micro-World section, dedicated to the inner world of gemstones, features an apatite crystal suspended over a cloud of rutile silk in a blue star sapphire, a diamond cut to showcase an octahedral-shaped cloud inclusion, a fractal-like hematite inclusion resembling a rose in aquamarine, and Chinese ruby with fluid inclusions in the shape of a snake and fish.
Gem News International
Finally, GNI correspondents from around the world report on the first rough Mozambican ruby auction held by Fura Gems, the identification of pink aventurine quartz with alurgite inclusions, spectroscopic characteristics of blue to violet spinel heated at low temperature, and the announcement of the GIA Library and Museum Facebook group.
Brooke Goedert is associate editor of Gems & Gemology at GIA in Carlsbad, California.