Unstable Colouration of Padparadscha-like Sapphires

Krzemnicki, Michael S. and Klumb, Alexander and Braun, Judith . (2018) Unstable Colouration of Padparadscha-like Sapphires. The Journal of Gemmology, 36 (4). pp. 346-354.

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Official URL: https://edoc.unibas.ch/79314/

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After the October 2016 discovery of a new gem deposit at Bemainty near Ambatondrazaka, Madagascar, a number of sapphires with padparadscha-like colour entered the trade. However, most of these stones were found to have unstable colour, which changes from pinkish orange to more-or-less pure pink after a few weeks in daylight. In this study, the authors investigate the colour stability of padparadscha-type sapphires of metamorphic origin—mainly those originating from Madagascar (Ambatondrazaka and Ilakaka) and Sri Lanka. The 48 samples could be separated into three groups after colour-stability testing: sapphires that did not show a noticeably different appearance (case A); sapphires with a slight-to-moderate colour difference within the padparadscha range (case B); and fancy-colour sapphires showing a distinct change in appearance that fell outside of the padparadscha range (case C). The last situation was especially common for the stones from Ambatondrazaka, thus revealing that careful colour-stability testing is mandatory for proper gemmological identification of any sapphire showing a yellow to orange colour component.
Faculties and Departments:05 Faculty of Science
05 Faculty of Science > Departement Umweltwissenschaften > Ehemalige Einheiten Umweltwissenschaften > Mineralogie-Petrographie
UniBasel Contributors:Krzemnicki, Michael S.
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:The Gemmological Association of Great Britain
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:23 Nov 2020 16:27
Deposited On:23 Nov 2020 16:27

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