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Updated: Jan 10, 2026
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Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
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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.
Scientific Reports
|November 23, 2025
Summary
This study introduces a fast method for identifying orange-red garnets using infrared spectroscopy. Manganese/iron ratios and iron content significantly influence garnet color, aiding in gemstone variety classification.
Area of Science:
- Gemology
- Materials Science
- Spectroscopy
Background:
- Garnet coloration is influenced by transition metal ions and crystal structure.
- Accurate identification of orange-red garnet varieties is crucial for the gemstone industry.
Purpose of the Study:
- To establish a rapid method for identifying orange-red garnet varieties.
- To correlate chemical composition with color parameters.
Main Methods:
- Infrared absorption spectroscopy was used to detect shifts in absorption peaks.
- Color parameters were quantified using the CIE 1976 L*a*b* color space under standardized illuminants (D65, A, F2).
- The influence of Mn/Fe ratio and Fe content on hue angle (h°) was analyzed.
Main Results:
- A correlation was found between infrared absorption peak shifts and garnet varieties.
- Illuminant A maximized chroma for red garnets, while F2 light optimally displayed orange-yellow garnets.
- D65 illuminant proved versatile for routine identification and evaluation.
Conclusions:
- The Mn/Fe ratio and Fe content are critical factors modulating the hue angle of orange-red garnets.
- This study integrates crystal chemistry and colorimetry for optimized gemstone presentation.
- The developed method offers practical strategies for the gemstone industry.
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