The Characterization Of Quantized Cr³⁺ Affecting The Color Of Ruby

Ruby is one of four kinds of precious gemstones, and has much market share. It is helpful of study in color evaluation of ruby and the relationship of color-causing ion and color Parameter to ruby evaluation index, and synthetic gem.In order to know the relationship of color and color-causing ion and Production Place, we get the L^*, C^*, ho, a^*, b^* and chromatic aberration from x—rite color i(?) color measurement instrument. And get the contents of trace element from LA-ICP-MS.In CIEL^*a^*b^* color space, uniformity of brightness is better than saturation and hue. Arraying rubies according brightness is in accord with feeling of human eyes. According to diamond classification system of GIA, color of ruby is divided four grades: E(excellence), V(vcry good), G(good), P(poor) when brightness is belong to 32-52.According to study of the relationship of contents of Cr³⁺ and color parameter, we get saturation and hue goes contrary to brightness when content of Cr³⁺ increase. When content of Cr³⁺ is less than 8000ppm, the color of ruby changes large with content of Cr³⁺ arise. When content of Cr³⁺is more than 8000ppm, the color of ruby changes small with content of Cr³⁺ arise. When content of Cr³⁺ is 8000ppm, the color of ruby is the best, at that time,L∈(21.27,57.03), hue is more than 5°. CIE LAB is sensitive to red, so it suitable to count chromatic aberration of ruby. But the uniformity of CIE LAB is not good, so it fit small chromatic aberration.According to study of influence of other trace elements to color, Titanium is good for saturation of ruby.Combining other study on content of trace elements of ruby and color characteristic in different places, we find: ruby in Myanmar is red, its saturation is about 15, its brightness is about 30 and its hue is about5°. Ruby in this color is the best quality and most expensive. Ruby in Sri Lanka is pink, its saturation is low, and brightness is high. Ruby in this color is most cheap. Ruby in Afghan is pink with high brightness.