几种常见蓝色宝石的色度学对比分析

Chromaticity Contrast Analysis of Several Common Blue Gemstones

蓝色蓝宝石、磷灰石、堇青石虽同为常见的蓝色相似宝石,但其颜色仍有许多差异,主观的颜色评价不能准确量化三种宝石的具体颜色差异。本文利用色度学原理,测量蓝宝石、磷灰石和堇青石样品的相关色度学数据,在CIE1931色度系统以及CIE1976 La^(*)b^(*)颜色空间系统下进行质量分析评价,将三种宝石的颜色划分为蓝色、蓝紫色、蓝青色、蓝绿色四种色调,同时发现蓝宝石显示了最多的蓝色调,磷灰石次之;蓝宝石更显示绿色调,磷灰石更显示黄色调。结果显示,蓝绿色调的蓝宝石彩度最差,纯蓝色色调和蓝紫色色调的蓝宝石有最佳颜色品质;蓝青色、蓝绿色色调的磷灰石有最佳颜色品质;堇青石的明度与彩度呈一定的负相关关系,蓝色、蓝紫色色调的堇青石有优异的彩度但明度较差,而蓝青色、蓝绿色色调的堇青石有良好的明度但彩度很差。由此可以推断出三种蓝色宝石颜色品质与色度参数之间的对应关系,为颜色质量分级提供科学理论依据。

Sapphire,apatite and cordierite are common blue gemstones that in some way similar,but there are still many differences in their colours.Subjective colour evaluation cannot accurately quantify the specific colour differences of the three gemstones.This study used the principle of chromaticity to measure the correlated chromaticity data of sapphire,apatite and cordierite.Quality analysis and evaluation were performed under the CIE1931 chromaticity system and CIE1976 L a^(*)b^(*)colour space system.The colours of the three gemstones can be divided into four hues:blue,blue-violet,blue-cyan and blue-green.The results show that sapphire shows the bluest hue,followed by apatite.Sapphire shows more green hue,and apatite shows more yellow hue.It is concluded that the blue-green sapphires have the worst chroma,pure blue and blue-violet sapphires have the best colour quality;blue-cyan and blue-green apatites have the best colour quality.The lightness of cordierite has a certain negative correlation with the chroma:blue and blue-violet hues of cordierite have excellent chroma but poor lightness,while blue-cyan and blue-green hues of cordierite have good lightness but poor chroma.From this,the correspondence between the colour quality and chromaticity parameters of the three blue gemstones can be deduced,which provides a scientific theoretical basis for colour quality grading.