Influence of Fe2+ on the Color Appearance of Yellow-Green Peridot
Twenty-eight yellow-green color of uniform, high clarity and similar thickness of 5 mm × 7 mm oval faceted peridots from Jiaohe Jilin province were examined by LA-ICP-MS and Color i5 to test their chemical compositions and L*, C* and ho. The correlations between Fe2+ and color parameters were analyzed, in order to establish the influence on the color appearance of Fe2+. The chemical formula of the twenty-eight peridots is (Mg1.84,Fe0.19)2.04[(Si0.982,Al0.001)0.983O4], which was calculated by oxygen atom. It reveals that 0.19 mol Fe2+ is concluded in one mol peridot, and Fe2+ is the colorant of peridot. Based on the CIE 1976 L*a*b* uniform color space, relationships between chromaticity coordinates a*, b* and chromaticity C* were analyzed by Two-way ANOVA, of which the results showing that the influence of b* on C* (rb*×C*=0.996) is much more prominent than a* on C* (ra*×C* = -0.383). By partial correlation analysis of the results calculated through CIE LAB color-difference formula, it can be discovered that lightness difference DL* has a better correlation with chromatic aberration DE* than DC* and DH*, whereas the significance level ρDC*×DE* > 0.05, rDH*×DE* > 0.05, it reveals that DE* is more sensitive to DL*. At the same time, L* changes the most with the contributions of Fe2+ compared with other parameters of peridot. It is concluded that, with the help of L*, Fe2+ has a further influence on the color appearance of peridot.
Yiwang Bao, Danyu Jiang, Li Tian and Jianghong Gong
W. X. Tang et al., "Influence of Fe2+ on the Color Appearance of Yellow-Green Peridot", Key Engineering Materials, Vol. 492, pp. 370-373, 2012