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Published on: April 14, 2020
Light source dependent colour perception in orange red garnets via spectroscopy and colorimetry
Meilin Zhu1, Pohsun Wang2, Ying Guo3
1Department of Gemology, China University of Geosciences (Beijing), Beijing, 100083, China.
Abstract:
The coloration of garnets is governed by transition metal ions and crystal structure. This study established a rapid variety identification method for orange-red garnets based shifts in infrared absorption peaks. We quantified color parameters under standardized illuminants (D65, A, and F2) using the CIE 1976 L*a*b* space. The results revealed that the Mn/Fe ratio and Fe content critically modulate the hue angle (h°) of orange and red garnets. Illuminant A maximises chroma for red varieties, while F2 light optimally displays orange-yellow garnets. D65 provides a versatile source for routine identification and evaluation. This integration of crystal chemistry and colorimetry offers actionable strategies for optimising orange-red gemstone presentation.
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