The lead article of the Summer 2017 Gems & Gemology profiles Russia’s Lomonosov diamond deposit, Europe’s first diamond locality and a producer of fancy-color diamonds. Other diamond-related articles recount the characteristics and formation theories of carbonado and the use of photoluminescence mapping to identify optical centers, synthetic origin, and treatment. The Summer issue also features a wall chart showing inclusions in sapphire, as well as articles on establishing nephrite color determination standards, properties of Vietnamese tourmaline, and the sapphire deposits of Montana.
GEOLOGY AND DEVELOPMENT OF THE LOMONOSOV DEPOSIT, NORTHWESTERN RUSSIA
While most Russian diamond mines are hosted by the Siberian craton, Lomonosov falls within the Baltic shield. Its Proterozoic geological setting location is likely responsible for its fancy pink diamond production. Authors Karen V. Smit and Russell Shor visited the Lomonosov deposit to tour the operations, processing, and sorting of Europe’s first diamond mine.
CARBONADO DIAMOND: A REVIEW OF PROPERTIES AND ORIGIN
This investigation into carbonado, a diamond aggregate with unusual textural features, proposes an extraterrestrial model for its genesis. Stephen Haggerty describes the known history, characteristics, and proposed origins for this remarkable material.
PHOTOLUMINESCENCE MAPPING OF OPTICAL DEFECTS IN HPHT SYNTHETIC DIAMOND
Photoluminescence (PL) mapping is a viable method for separating natural, synthetic, and treated gem specimens. Lorne Loudin performs PL mapping on a synthetic diamond of mixed type and identifies optical defects incorporated into growth sectors, demonstrating the usefulness of this technique.
AN UPDATE ON TOURMALINE FROM LUC YEN, VIETNAM
Tourmaline has been from Vietnam’s Luc Yen district since the 1980s. A team of researchers led by Nguy Tuyet Nhung presents the characteristics of the tourmaline found in this gem-rich region, comparing the specimens with data from the literature.
CHARACTERIZATION OF MG AND FE CONTENTS IN NEPHRITE USING RAMAN SPECTROSCOPY
Color determination of nephrite jade by visual observation can be problematic. Xiaoyan Feng and her coauthors propose a measurement based on nephrite’s Mg+2 and Fe+2 content to define boundaries between colors and to establish a standard for the highly sought fine white material.
INCLUSIONS IN NATURAL, SYNTHETIC, AND TREATED SAPPHIRE
The second wall chart in a series documenting common inclusions focuses on natural, synthetic, and treated sapphire. Inclusion specialists John Koivula, Nathan Renfro, Jonathan Muyal, and Shane McClure contributed photomicrographs to the reference chart.
BIG SKY COUNTRY SAPPHIRE: VISITING MONTANA’S ALLUVIAL DEPOSITS
Since the late nineteenth century, the western U.S. state of Montana has long been a source of alluvial sapphire. Tao Hsu and her coauthors survey mining and the importance of gem tourism to the areas, noting that larger, mechanized operations are expanding production at these sources.
Specimens seen at GIA’s labs include a diamond with concentric inclusions, natural conch “rosebud” pearls, and CVD synthetic diamond overgrowth on a natural diamond.
G&G’s newest section describes a mysterious iridescence present in a rough aquamarine, a Christmas tree-shaped laser manufacturing remnant in a diamond, and a ruby treated with red oil.
GEM NEWS INTERNATIONAL
The Summer GNI section features reports on a newly discovered sapphire deposit in Ethiopia, dyed yellow bead-cultured pearls imitating South Sea cultured pearls, and a tri-color-change holmium-doped synthetic cubic zirconia.
2017 G&G CHALLENGE
The 2017 G&G Challenge is still open! 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 2017 issue. Mail-in cards and online entries for the Challenge must be submitted by Friday, August 11, 2017.