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Karampelas S.,Gubelin Gem Laboratory | Lombard A.,Cendanda Indopearls Atlas South Sea Pearls
Gems and Gemology | Year: 2013

Experimental saltwater cultured pearls produced after xenotransplantation between P. margaritifera and P. maxima were studied using UV-Vis-NIR and PL spectroscopy as well as radiography. The results further demonstrate that the graft (saibo) largely determines the coloration and nacre thickness of the cultured pearl. © 2013 Gemological Institute of America. Source

Karampelas S.,Gubelin Gem Laboratory | Fritsch E.,University of Nantes | Gauthier J.-P.,University of Lyon | Hainschwang T.,GGTL GemlabGemtechlab Laboratory
Gems and Gemology | Year: 2011

Natural-color saltwater cultured pearls from Pinctada margaritifera were studied by diffuse reflectance UV-Vis-NIR spectroscopy to identify the absorption features associated with their various colors. Nine patterns observed in the visible range demonstrated that individual colors are caused not by one pigment but by a mixture of pigments. © 2011 Gemological Institute of America. Source

Karampelas S.,Gubelin Gem Laboratory | Worle M.,Laboratory for Conservation Research | Hunger K.,Laboratory for Conservation Research | Lanz H.,Collections and Documentation
Journal of Raman Spectroscopy | Year: 2012

The gems that adorn two golden chalices from Einsiedeln Abbey (Switzerland) crafted in 1609 and 1629 were investigated using Raman spectroscopy. The results were also compared with those obtained by other non-destructive means such as microscopy and energy-dispersive X-ray fluorescence. The chalice made in 1609 was adorned with 16 corundum (15 rubies and 1 sapphire), four garnets (two almandine and two grossular), seven quartzes (six amethysts and one citrine) and one peridot (forsterite olivine). All pearls of this chalice were found to be from a saltwater mollusc. The chalice crafted in 1629 was adorned with 23 diamonds. Compilation of all the results does not exclude that the stones mounted to the chalices are of 'oriental' origin. However, more research needs to be done by additional spectroscopic means to shed more light on their origin. Copyright © 2012 John Wiley & Sons, Ltd. Source

Huong L.,Vietnam National University, Hanoi | Hager T.,Johannes Gutenberg University Mainz | Hofmeister W.,Johannes Gutenberg University Mainz | Hauzenberger C.,University of Graz | And 5 more authors.
Gems and Gemology | Year: 2012

This article describes the major gem materials of Vietnam, together with their new finds and recent production. The gemological properties and chemical composition of ruby, sapphire, spinel, tourmaline, garnet, and peridot from the most important Vietnamese sources are updated. Other gems such as aquamarine, green orthoclase, topaz, zircon, quartz, and pearls are briefly discussed. Commercially significant deposits of ruby, blue and fancy sapphire, and spinel are located in two northern provinces: Yen Bai (Luc Yen and Yen Binh Districts) and Nghe An (Quy Chau and Quy Hop Districts). Large volumes of blue, green, and yellow sapphire come from the Central Highlands provinces of Dak Lak and Lam Dong, as well as the southern provinces of Dong Nai and Binh Thuan. Of secondary commercial importance are the tourmaline and garnet from Yen Bai and the peridot and zircon from the Central Highlands. © 2012 Gemological Institute of America. Source

Coccato A.,Ghent University | Karampelas S.,Gubelin Gem Laboratory | Worle M.,Collection Center | Van Willigend S.,Swiss National Museum | Petrequin P.,University of Franche Comte
Journal of Raman Spectroscopy | Year: 2014

Raman spectroscopy was used for the characterization of seven gem quality green 'jade' samples and three green 'jade' samples of archaeological importance. The results were also compared with those acquired by other nondestructive techniques such as classical gemology, energy-dispersive X-ray fluorescence (EDXRF), ultraviolet-visible-near infrared (UV-Vis-NIR) in absorption, Fourier transform infrared spectroscopy (FTIR) in absorption and micro-FTIR in reflectance. Five samples of gem quality and two samples of archaeological interest were found to be 'jadeite jade', whereas two samples of gem quality and one sample of archaeological interest were 'omphacite jade'. Raman spectroscopy is found to be the most efficient method for their characterization. The results were confirmed with EDXRF and micro-FTIR in reflectance. Data acquired using classical gemology, UV-Vis-NIR absorption and FTIR absorption spectroscopy were similar on 'omphacite jade' and 'jadeite jade'. Copyright © 2014 John Wiley & Sons, Ltd. Source

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