Munsell Rectification On Metamerism Of Green Jadeite Jade

Based on the colorimetric system, it does some research on the phenomenon of metamerism in green jadeite jade, drawing a conclusion of the effect that every color parameter has on the metameric character. In order to improve the commercial application, adding some naked eyes factors and using hue and chroma means to explain the lightness differences between green jadeites under subjective and objective conditions separately on the basis of the Munsell color cards'subjective various color lightness matching experiments.Using Color i5 spectrophotometer to measure 288 green arc jadeite jades under standard light source D₆₅ and testing light source A to get their color data. Selecting those samples with M_t<1 after light source has changed to do T testing, the analyzing result shows that all of the color parameters like L^*a^*b^*C^*h₀ change when the light source transferred from D₆₅ to A, but they have different influence on the metameric character, among which b^* makes the most significant effects.Selecting two groups samples 100 pairs ranging from M_t<1 to 4t<5, put their color parameters on the L^*a^*b^* color space's transverse section to analyze qualitatively that green jadeites pairs with more yellow hue or blue hue which is not vivid, their M_t parameters are much higher, when the light source conditions or observers change, they are lean to have different colors, so they have bad metameric characters.Selecting those green jadeite jades pairs with similar C^*(chroma), their subjective and objective lightness differences lie on the effect caused by the hue and chroma, +b^* is higher, that is yellower, which leads to higher lightness under naked eyes, +b^* is lower, that is greener, meaning lower lightness under naked eyes. As to those pairs that can not be explained from the perspective of hue factor, using Munsell true color system to obtain the effect of chroma factors in details.Under light source D₆₅, selecting color cards with hue 5GY, 5G and 5BG, lightness 2,4,5,7, chroma ranging from low to high to do subjective various color lightness matching experiments with different neutral cards by 5 normal color vision observers. It concludes the formula Vs=V+0.125C, which applies to revise the subjective and objective lightness differences of green jadeites, but applies to green jadeites with widely different chroma much better.