Journal of Gemmology: Jadeite, Morganite, and more
Gary Roskin –
Roskin Gem News Report –
jade is known mainly from Myanmar, but
similar material is also on the market from Guatemala and
elsewhere. Value differences between jades from various
localities are creating demand for laboratories to
determine their geographic origin, and techniques for
doing this are described on pp. 124–144 of this issue.
The top-quality Burmese jade cabochon in this pendant
measures 35.95 × 30.65 × 15.47 mm. Photo courtesy of
Stanley Chu, On Tung Jewellery, Hong Kong.
Another impressive collection of gemmological articles in this latest edition of The Journal of Gemmology, Gem-A’s professional peer-reviewed periodical, compiled by Brendan Laurs, Editor-in-Chief.
Represented by the cover, the feature story “Geographic Origin Determination of High-quality Green Jadeite-Omphacite Jade (Fei Cui) from Myanmar, Guatemala and Italy Using Statistical Processing Coupled with Spectroscopic and Chemical Analyses“ looks at twenty-seven samples of high-quality green jadeite-omphacite jade from Myanmar, Guatemala and Italy to see if new methodology for geographic origin determination could be applied. And it looks promising.
Another feature that peaked our interest is titled “Gamma Spectroscopy—A Possible Identification Method for the Artificial Irradiation of Morganite.” As you probably already know, gamma irradiation of morganite (to enhance its pink color) has been impossible (or very difficult) to identify since both laboratory and natural irradiation processes involve the same colouration mechanisms. Here is discussed a new testing procedure that is looking for radioactive Cs isotopes (e.g. 132Cs and 134Cs) detectible through gamma ray spectroscopy, which may actually result in the labs being able to identify gamma irradiation treatment in morganite. Like the new jadeite testing above, proving irradiation of morganite is not quite there yet, but it too looks very promising.
The JoG’s Gem Notes is packed with several new gem finds, including rainbow moonstone, cassiterite, azurite, rhodonite, orange hackmanite, and more. One new find reported in a feature article is “The Sinoniki Spessartine Deposit in Longido, Tanzania—A New Source of Bright Orange Spessartine (‘Mandarin’) Garnet.” According to the report, the Sinoniki spessartine deposit produces material that has a distinct chemical composition, resulting in the laboratories’ ability to identify source origin.
Tap here if you are interested in reading a copy of this latest Journal of Gemmology.
