金色南洋珠与染色金珠的谱学特征对比
Spectroscopy Characteristic Comparative Study of Golden Seawater Cultured Pearl from South Sea and Dyed Seawater Cultured Pearl
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摘要: 近年来在中国市场中出现不同类型的染色金珠, 很难通过肉眼和镜下观察将其与金色南洋珠区分。为了找到区分两者的无损鉴定依据, 实验对比金色南洋珠和部分类型的染色金珠的紫外-可见光谱及拉曼光谱特征, 结果发现:(1)金色南洋珠的拉曼光谱谱线无毛刺、荧光背景弱、文石振动峰清晰明显。若拉曼光谱毛刺多、荧光背景强、文石振动峰消失, 应为染色处理金珠; (2)金色南洋珠的紫外-可见光谱具有两处特征吸收带, 285nm处的窄吸收带和360~440nm处的宽吸收带。若紫外-可见光谱在285nm处的吸收带消失或明显减弱, 同时360~440nm处的宽吸收峰位移至420nm以后或吸收带变窄, 或分裂为两处独立的吸收带, 可判定为染色金珠。若紫外-可见光谱在360~440nm处的吸收带与金色南洋珠相似或位移不明显时, 紫外-可见光谱特征易引起误判, 不应作为染色处理的鉴别依据。由此可见, 部分染色金珠的谱学特征与金色南洋珠仍有重合, 在鉴定过程中, 应结合镜下观察、紫外-可见光谱、拉曼光谱等测试手段综合判定, 对存有疑问的样品, 应谨慎判断。Abstract: 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.