Quality grading system of Jadeite Jade green based on three colorimetric parameters under CIE standard light sources D 65 CWF and
The article deals with the color changes appearing under different light sources due to the individual and combined effects of lightness, hue and chroma. As a result, a green color grading system is created based on color evaluation from its appearance. We tested the color of 277 pieces of green jadeite specimens using Color i5 spectrophotometer based on CIE 1976 L*a*b* uniform color space and Munsell color matching system. It was concluded that the CIE standard light source D65 is more suitable for assessing jadeite jade green compared with the CIE standard light sources CWF and A. After the alternate use of light sources D65 and A, the color shows a slight yellow tone. While the light source changed from D65 to CWF, the lightness of jadeite jade green decreased sharply. The jadeite jade green concentrates on the lightness scope of (5.64, 61.96) and most of them focus on the scope of moderate to brighter lightness of (30, 60) It is shown that the optimal green of jadeite jade is deep and dark. The support vector machine (SVM) predicts that 20 of 35 unclassified jadeite jade cabochons should have a corresponding level based on the color green grading system of jadeite jade. Taking into account the combination of theory and practice, the conclusion is drawn that the color green grading system of jadeite jade should be calculated in the CIE 1976 L*a*b* uniform color space combined with the Munsell color system for physical color comparison.