Spectroscopy Characteristic Comparative Study of Golden Seawater Cultured Pearl from South Sea and Dyed Seawater Cultured Pearl

In recent years, it is hard to distinguish dyed golden seawater cultured pearl from the golden ones without dyeing on the market by naked eyes. In order to solve the problem, surface magnification, UV-Vis spectra and Raman spectra of the dyed golden seawater cultured pearls and golden seawater cultured pearls from South Sea are tested and comparatively studied. According to Raman spectrum, when it shows strong Raman fluorescence, no clear peaks and missing aragonite Raman peaks, the sample must be dyed. It can be judged as undyed pearl when spectrum shows weak Raman fluorescence, clear peaks and obvious aragonite Raman peaks. According to tests of UV-Vis spectrum, there are two major groups ofabsorption bands in the UV-Vis spectrum of the golden seawater cultured pearl from SouthSea One narrow band is at 285 nm and the other wide band is at 360~440 nm, These two absorption bands are stable in different batches of the golden seawater cultured pearls from South Sea, which could be used as the standard spectrum of the golden seawater cultured pearl. When the absorption band of UV-Vis spectrum at 285 nm recedes or disappears, and the absorption band at 360~440 nm splits into two independent bands or red shifts to 420 nm or get narrower, the sample must be dyed. When the absorption band at 360~440 nm is similar to that of un-dyed one or shifts not obviously, the UV-Vis spectrum is not effective. The judgment needs a variety of ways to be combined with.