Cultured pearls with a chocolate color have entered the market from several sources. Analytical tests indicate that the organic components in black cultured pearls may have been partially bleached to create the brown color. The treated cultured pearls can be identified by visual observation, unusual coloration, fluorescence, UV-Vis-NIR reflectance and Raman spectroscopy + trace element composition.
Useful link:
http://ballerinapearl.com
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