The Significance of Photoluminescence Spectra With the Excitation Wavelength of 473 nm for the Indication of Pearl Types and Color Origin

In this paper, photoluminescence spectra with excitation wavelength of 473 nm are used to study and compare the photoluminescence features of pearls of different colors. The resalts show that there are obvious differences in the photoluminescence spectra of pearls of different color types obtained urkler the wavelength of excitation light source, which has important indication significance for the origin of the color of pearls (1) Most of the gray and yellow pearls with untreated color range from 570 to 600 nm, which is consistent with the main luminescent peaks of aragonite. It is inferred that the color origin is mainly related to the arrangement structure of aragonite. (2) The strongest luminescence peaks of untreated purple and orange pearls are also located in the range of 570 similar to 600 nm, related to aragonite Still. a series of small sharp luminescence peaks, which have no relationship with aragonite, also appear in the range of 500 similar to 570 nm. It is inferred that the color is related to the arrangement structure of aragonite and influenced by organic matter it such pearls. (3) The main photoluminescence peak of untreated black pearls occurs from 800 to 900 nm and the origin of its color may be mainly related to the organic matter in the pearls. (4) The strongest photoluminescence peak of most dyed pedels is located in the range of 650 similar to 750 nm, and the photoluminescence peak is mainly related to the dye. The similar photoluminescence characteristics of dyed pearls of different colors indicate that the main chromic components of the dyes currently psed in the market have similar group compositions. The related research results can provide a more scientific basis for detecting and identifying pearls and studying color origin.