Research Library

Gemstones and the fascination of colour

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Christie’s Hong Kong Spring Auction lecture by Dr. Michael Krzemnicki. “Gemstones and the fascination of colour”

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Spinel: a gemstone on the rise

Talk given by Dr. Michael Krzemnicki in Hong Kong in 2010 about spinel, a gemstone increasingly in vogue. History, sources, origin determations, synthetics and treatments.

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How to get the blues of the pink: detection of low temperature treatment of pink sapphires

Latest research on detection of low temperature treatment of pink sapphires. Presentation by Dr. Michael Krzemnicki of SSEF.

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Appearance of new bead material in cultured pearls

Abstract: A range of different materials has already been used as cores in beaded cultured pearls, and now two new alternative options, baroque shaped shell beads and Chinese freshwater cultured pearls, are being used. Experiments with beads of the latter, approximately 6.5 mm across, have been carried out with marine Pinctada maxima and Pinctada margaritifera oysters. After 13 months, nearly 200 pearls of each kind were harvested. Cross sections and further observations of resulting pearls are described. X-radiographs and X-ray microtomography are found to generally deliver clear evidence for identification. These pearls have beenfound to be very suitable for subsequent drilling. Natural pearls also have been used as nuclei for producing cultured pearls. The material used is either non-nacreous, brown or of an unattractive appearance. This new kind of cultured pearl is diffi cult to identify, because the radiographic structures of the natural cores are masking these cultured pearls.

Journal of Gemmology (2010)

Author(s): H.A. Haenni, M.S. Krzemnicki, L.E. Cartier

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