Environmental Issues on Color Quality Evaluation of Blue Sapphire based on GemdialogueTM Color Comparison Charts

This article seeks to evaluate color quality of blue sapphire and also address environmental impacts related to precious stones. Mining for gold, silver, diamonds, sapphires, gemstones, and other metals can result in water pollution, greenhouse gas emission, and soil erosion. Through the measurement, screening and analysis of color parameters of Gem Dialogue TM Color Comparison Charts, the feasibility of its application to the color evaluation of blue sapphire was explored in terms of ecological evaluation. Charts with strong blue tone in GemdialoguetTM Color Comparison Charts--charts G2B, CYAN, B, P2B and B2P--were measured under illuminants A, D65 and CWF, by X-rite SP60 Portable spectrophotometer. The law of the charts color variation, environmental issues and the influence of illuminant variation on color were explored. And D65 is recommended to be used as the color comparison and ecological evaluation illuminant of blue sapphire. Screen the measured data in reference to the specified color range of Chinese National Standard “GB/T 32862-2016 Sapphire Grading”. The valid color data was classified into five categories through K-Means clustering analysis of SPSS21.0 and taxonomic ecology, and the taxonomy accuracy rate reached 98.3% by the verifying of Fisher analysis. Combined with the environmental effect of color simulation, the result of classification was ecologically accurate and ideal. Applying the GemdialogueTM Color Comparison Charts to the color quality evaluation of blue sapphire is practicable. By screening the data according to the environmental characteristics of different gems, this method can be extended to help establish the color evaluation system of other blue color gems. It is also suggested to support organizations working to improve the global mining industry. Ethical Metal Smiths and Fair Jewelry Action are two such organizations.