无色蓝宝石的宝石学特征研究

Research on Gemological Characteristics of Colorless Sapphire

摘要: 蓝宝石的主要成分为Al₂O₃，其作为世界五大名贵宝石之一，在世界上广受欢迎。文章主要是针对无色蓝宝石的宝石学特征、优化处理进行讨论。首先阐述了近年来蓝宝石的宝石学特征、内部包体、优化处理的研究现状以及研究背景，明确本次研究探讨的对象是无色蓝宝石的宝石学特征以及优化处理工艺(热处理、表面扩散处理)。在查阅文献资料的基础上，通过常规的宝石学仪器对无色蓝宝石的宝石学基本参数进行研究，结果表明无色蓝宝石与其他颜色的蓝宝石的宝石学参数无太大差别。通过红外光谱、紫外可见光吸收光谱测试对无色蓝宝石的谱学特征进行研究，在综合分析前人结论的基础上，得出在测试条件相同情况下，各种颜色的蓝宝石的红外反射谱吸收峰的位置大多相似，在400~500 cm⁻¹都会存在若干个吸收峰，在600 cm⁻¹附近均会出现吸收峰；对比不同颜色的蓝宝石的紫外可见光吸收光谱，发现无色蓝宝石在377 cm⁻¹、387 cm⁻¹、450 cm⁻¹处有吸收峰，但是450 cm⁻¹处吸收峰强度较小，可见该处吸收对宝石颜色的影响较大。通过对无色蓝宝石的基本宝石学参数以及谱学特征的归纳总结，分析出无色蓝宝石与其他色调的异同点，为之后的无色蓝宝石研究提供参考。

Abstract: Sapphire is mainly composed of Al₂O₃. Sapphire is one of the world’s five most precious stones and is very popular in the world. This paper mainly discusses the gemological characteristics and optimal treatment of colorless sapphire. Firstly, the gemological characteristics of sapphire, the research status and research background of internal inclusions and optimal treatment in recent years are described. It is clear that the object of this research is the gemological characteristics of colorless sapphire and the optimal treatment process (heat treatment, surface diffusion treatment). On the basis of literature review, the basic gemological parameters of colorless sapphire are studied by conventional gemological instruments. The results show that the gemological parameters of colorless sapphire are not much different from those of sapphire of other colors. The spectral characteristics of colorless sapphire are studied by infrared spectrum and ultraviolet-visible absorption spectrum. Based on the comprehensive analysis of previous conclusions, it is concluded that under the same testing conditions, the infrared reflection spectrum and absorption peak positions of sapphire of various colors are mostly similar. There are several absorption peaks in 400~500 cm⁻¹ and absorption peaks in the vicinity of 600 cm⁻¹. Comparing the ultraviolet and visible light absorption spectra of sapphires with different colors, it is found that colorless sapphires have absorption peaks at 377 cm⁻¹, 387 cm⁻¹ and 450 cm⁻¹, but the intensity of absorption peaks at 450 cm⁻¹ is small, which shows that absorption at this place has a great influence on the color of the sapphire. Based on the summary of basic gemological parameters and spectral characteristics of colorless sapphire, the similarities and differences between colorless sapphire and other colors are analyzed, which can provide reference for the future research of colorless sapphire.