Spectroscopic Analysis of Coated Sapphire

Sapphire with bright and uniform colour, high transparency, andbright lusterhas very high value in the trade. In order to improve its commercial value, people have putting great efforts working on ways to improve the colour of sapphire. The traditional treatment methods include dyeing, heat treatment, surface diffusion treatment, beryllium diffusion treatment and coating. Recently, people have paid attention to enhance the colour of sapphire by coating its surface with different colours to optimize the appearance of the sapphire as well as to increase its commercial value. Vacuum coating has the advantages of low energy consumption, little pollution, low cost and good decoration effect. The use of vacuum coating technology to improve the colour of sapphire is becoming more and more popular. All samples in this paper have achieved surface colour modification through vacuum magnetron sputtering coating. In order to better study the application of coating technology in the sapphire surface treatment, in this paper, the sapphire specimens in different colours without/with coating (including colourless, yellow, indigo and green) were selected to carry out the gemmological test, infrared spectrum analysis and X-ray fluorescence spectrum analysis, to summarize the surface features of sapphire with different colour coatings and analyze the chemical composition of coating films with different colour as well as the relationship of coating film composition and colours.