天然黄色与染色Akoya珍珠的光谱学特征  

Spectroscopic Characteristic of Natural and Dyed Yellow Akoya Pearl

作　　者：林默青 郜玉杰 LIN Moqing;GAO Yujie(Guild Gem Laboratories,Shenzhen 518020,China)

机构地区：[1]吉尔德宝石实验室,广东深圳518020

出　　处：《宝石和宝石学杂志（中英文）》2022年第5期94-100,共7页Journal of Gems & Gemmology

摘　　要：近年来,黄色Akoya珍珠在市场上越来越受欢迎,但相关研究资料较少。染色Akoya珍珠已经作为替代品出现在市场交易中。选取24颗天然黄色和染色Akoya珍珠样品,通过X射线荧光光谱仪、紫外-可见光-近红外反射光谱和拉曼光谱等测试手段对珍珠样品进行测试分析。结果表明,天然黄色Akoya珍珠样品中存在两种色素类型:一种是以C-C和C C为主要结构的线性多烯分子,拉曼位移在1130 cm^(-1)和1530 cm^(-1)附近;另一种可能是卟啉类化合物,拉曼位移在1385 cm^(-1)和1573 cm^(-1)附近,且UV-Vis-NIR光谱有2个特征吸收带(330~385 nm和385~430 nm)。第二类色素的光谱特征与天然南洋金珠一致。染色Akoya珍珠样品可通过表面或珠孔部位染料富集的特征以及结合UV-Vis-NIR光谱(280 nm处的吸收明显减弱,以330 nm和460 nm为中心有两个弱吸收带)和拉曼光谱(缺失天然多烯或卟啉的色素峰)进行鉴别。In recent years,yellow Akoya pearls have become increasingly popular in the market,but the gemmological characteristics research are relatively scarce.In addition,dyed yellow Akoya pearls have already appeared in the trade as a substitution.In this paper,24 pieces of natural and dyed Akoya pearl samples were selected and analyzed by X-ray fluorescence spectrometer(XRF),UV-Vis-NIR reflection spectroscopy,and Raman spectroscopy.2 types of pigments were identified in natural yellow Akoya pearl samples:One is polyene pigment with C-C and C C as the main structure,and the Raman shift is around 1130 cm^(-1) and 1530 cm^(-1);the other may be a kind of porphyrins,and the Raman shift is around 1385 cm^(-1) and 1573 cm^(-1),and the UV-Vis-NIR spectra show 2 characteristic absorption bands(330-385 nm and 385-430 nm).The spectra of the second pigment type are consistent with golden South Sea pearls.Dyed Akoya pearl samples can be identified by dye concentration on surface pits or along the drill hole.A combination of UV-Vis-NIR spectra and Raman spectra is necessary when surface features are absent.The UV-Vis-NIR spectra of dyed pearls show a weaker absorption at 280 nm,and two absorption bands centered at 330 nm and 460 nm,which are different from the reflectance spectra of natural yellow pearls.The Raman spectra of dyed Akoya pearls lack Raman shifts of natural pigments.

关 键 词：Akoya珍珠 染色处理 紫外-可见光-近红外反射光谱 拉曼光谱 多烯色素 卟啉 

分 类 号：TS93[轻工技术与工程]