Gems & Gemology Gems & Gemology, Winter 2012, Volume 48, No. 4

Update on the Identification of Dye Treatment in Yellow or “Golden” Cultured Pearls

Chunhui Zhou, Artitaya Homkrajae, Joyce Wing Yan Ho, Akira Hyatt, and Nicholas Sturman

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Dye treatments in yellow or “golden” cultured pearls have improved to the point that some samples show little surface evidence. In addition to routine gemological observations, analytical techniques such as UV-Vis reflectance and Raman photoluminescence (PL) spectroscopy are critical to identifying the treatment. This study demonstrated three indications of dye treatment: broad reflectance features between 410 and 450 nm, the lack of a reflectance feature at 350 nm in the UV-Vis spectra, and intense fluorescence in the visible spectrum under 514 nm wavelength laser excitation. These diagnostic features may be used independently, even when no visual evidence of a dye exists.