拼合珊瑚的鉴定特征

珠宝市场上见到的大尺寸珊瑚有增多趋势,这类珊瑚多为珊瑚小料和胶结物拼合而成,前人研究未对其鉴定特征进行系统总结.笔者结合长期宝石检测工作认识,对目前市场上常见的两类拼合珊瑚的鉴定特征进行了系统研究和阐述.其中,一类拼合珊瑚由珊瑚小料和胶结物组成,另一类拼合珊瑚由珊瑚小料、人工胎体材料和胶结物组成.放大检查和紫外荧光观察发现,拼合部位的胶结物、胎体材料与主体红珊瑚在外观及发光性特征上存在差异明显;红外光谱测试结果进一步确定胶结物的主要成分为甲基丙烯酸甲酯和环氧树脂,部分拼合珊瑚依附的胎体材料主要为醇酸树脂（掺有碳酸盐粉末）和氰基丙烯酸乙酯.结果表明,放大检查、紫外荧光观察和红外光谱测试的综合运用,能够快速、准确、有效地鉴别拼合珊瑚.

Identification Characteristics of Composite Coral

Recently, the quantity of coral products with large size is increasing in the jewelry market. In fact, these large size coral products are mainly suspicious composite corals, which are combined by coral fragments and cements. There is little systematic summary on the i- dentification characteristics for these corals. In this paper, the identification characteristics and testing methods are summarized and discussed relying on long-term experiences and re- searches at gemstone testing center. It is found that there are two types of the composite cor- als. The type I is composed of coral fragments and cements, while type ]l consists of coral fragments, artificial matrix materials and cements. Magnification and ultraviolet fluorescence of the composite corals were observed. The appearance and luminescence characteristics were distinctive different between cements, matrix materials and the main part of coral products. By using infrared spectrometer to confirm the compositions of cementing material, it is found that they are mainly methyl methacrylate and epoxy resin and the compositions of some of the matrix materials detected from certain composite corals are mainly alkyd resin （mixed with carbonate material powder） and ethyl cyanoacrylate. Comprehensive applications of magnification and ultraviolet fluorescence observation with infrared spectrometer would be used to identify composite coral quickly, accurately and effectively.