Visible Absorption Spectrum Representation of Tahitian Black Pearls and Treated Pearls

The visible absorption spectra of a number of Tahitian black pearls,Pinctada magaritifera,dyed freshwater pearls and Hyriopsis cumingi have been tested by the USB 2000 Fiber Optic Spectrometer.The results show that the three particular absorption bands(a,b and c) of Tahitian black pearls and Pinctada magaritifera are different from that of the dyed freshwater pearls and Hyriopsis cumingi.Therefore,the visible absorption spectra of the pearls have the significance in the identification of Tahitian black pearls and dyed freshwater pearls.Some samples are tested by Raman spectrometer and the origin of the visible absorption spectra of Tahitian black pearls is studied.