The Impact of Munsell Neutral Grey Backgrounds on Tsavorite’s Color and Study on the Evaluation Method of Color Gem Cutting

Abstract

Tsavorite’s color is not only affected by its internal components, but also by external factors. This paper studies the neutral grey background and cutting on the impact on color. Under a 6504K fluorescent lamp, by changing the Munsell neutral gray backgrounds from N9.5 to N3, we discovered that N9.5 was the best background for tsavorite color grading. In this paper, the feasibility of taking color by photography is studied. The regression models R2 between the photogrammetry (PM) and the colorimeter (CM) were above 86.99% for all of the color parameters (L*, a*, b, C, and h*), allowing the PM data to be used to predict the CM color values. Photographs were taken before and after the cutting to document the color shift. Comparing the L* and C* before and after cutting, the color concentration score was 100–90 if both L* and C* were optimized, 80–70 if only one parameter was optimized, and 70–60 if neither was. The value of ΔL* in the color histogram serves as a measure of the gemstone’s color scintillation; the greater the value of ΔL*, the stronger the scintillation.