Cr3+ Effect on the Correlation between Lightness Difference and Color Difference of Ruby Red

摘要

The correlations between of lightness,chroma,Cr3+ and color index were studied to analyze the impact of all these three elements on ruby red color; and with the color difference research,the lightness difference is testified to be the key affecting color appearance. Based on the uniform color space CIE 1976L*a*b*,the ruby displays the best red color when the content of Cr3+ is within (1555,5183ppm),L*∈ (32.64,44.25) and ho ∈ (354.14,0.7). With the help of partial correlation analysis of color difference,it is illustrated that the correlation between △L* and △E* (r=0.999) is relatively higher than that between △L* and △E* (F0.948); and with high significance level (ρ= 0.129) of △H* and △E*. it shows that △H* has little impact on △E*. It is concluded that the color change of ruby from red to purple are mostly affected by lighffiess change; lightness difference should be considered as the most important factor when evaluating the red color of ruby,and then followed by the chroma and hue jointly.