澳大利亚绿玉髓显色背景研究及颜色评价

Study on the Color Background and Color Evaluation of Australian Chrysoprase

本文基于CIE 1976 L~*a~*b~*均匀色空间,利用红外光谱仪、X射线荧光光谱仪、便携式X-Rite SP62分光光度计、Munsell非彩色色卡等仪器设备对30颗澳大利亚绿玉髓样品进行了宝石学及色度学测试,并对澳大利亚绿玉髓提供了颜色评价方案。红外光谱分析显示,石英为绿玉髓的主要矿物成分,局部吸收峰缺失可能与石英岩质玉的结晶度相关;使用X射线荧光光谱仪对绿玉髓化学元素进行测试发现,绿玉髓颜色饱和度与Ni含量呈正相关;在D65荧光灯下,使用便携式X-Rite SP62分光光度计以10个Munsell非彩色色卡为背景,测试得到样品的颜色参数。经研究发现,不同的背景对绿玉髓的颜色具有很大影响并且在N9.5背景下绿玉髓能展现出最佳的饱和度。以Munsell N9.5为背景,采用K-均值聚类分析和Fisher判别式分析方法,将绿玉髓颜色从优到劣依次分为浓彩、深彩和中彩三组。

Based on CIE 1976 L~*a~*b~* uniform color space, the gemmology and chromaticity of 30 chrysoprase samples were analyzed by means of infrared spectrometer, X-ray fluorescence spectrometer, portable X-Rite SP62 spectrophotometer, Munsell non-color card, and the color evaluation scheme of chrysoprase was provided. Infrared spectrum analysis shows that quartz is the main mineral component of chrysoprase, and the lack of some absorption peak may be related to the crystallinity of quartzite jade. Using X-ray fluorescence spectrometer to test the chemical elements of chrysoprase, it is found that the chroma of chrysoprase is positively related to the content of Ni. Under the condition of D65 fluorescent lamp(color temperature 6504 K) as the light source, the color parameters of the samples were obtained by using portable X-Rite SP62 spectrophotometer with 10 Munsell non-color cards as the background. It is found that different background has a great influence on the color of chrysoprase, and chrysoprase can show the best chroma under N9.5 background. With Munsell N9.5 as the background, using K-means clustering analysis and Fisher discriminant analysis, the color of chrysoprase was divided into three groups, Fancy intensity, Fancy deep and Fancy.