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Quantitative definition of strength of chromophores in gemstones and the impact on color change in pyralspite garnets.

Quantitative definition of strength of chromophores in gemstones and the impact on color change in pyralspite garnets.

Authors :
Sun, Ziyin
Palke, Aaron C.
Renfro, Nathan D.
Rizzo, Jessa M.
Hand, Dylan B.
Sanchez, Diego
Source :
Color Research & Application. Oct2022, Vol. 47 Issue 5, p1134-1154. 21p.
Publication Year :
2022

Abstract

The color of most garnets is derived from multiple color‐producing elements (chromophores). In this study we selectively isolate the ultraviolet–visible–near infrared (UV–Vis–NIR) spectra of four major chromophores (Fe2+, Mn2+, Cr3+ and V3+) by collecting and extrapolating the spectra of four representative pyrope‐almandine‐spessartine (pyralspite) garnets. In order to study the color strength of these isolated chromophores and their impact on color change in garnet, we have proposed a new quantitative definition of strength of a chromophore. With the isolated garnet chromophore spectra, hypothetical garnet spectra with various chemical compositions can be simulated. By using these hypothetical garnet spectra, the impact of each chromophore on the color change behavior in pyralspite garnet was also quantitatively studied. Most pyralspite garnets can be successfully modeled using these four chromophores, however, this model cannot adequately describe those garnets containing the Fe3+/Fe2+ intervalence charge‐transfer transitions. Finally, a comprehensive excel data processing template (Appendix 3) written with VBA macro code was generated to help other researchers calculate colorimetric parameters and color panels from UV–Vis–NIR spectrum. In the template, we provided multiple types of conversion matrices and power distribution curves of different illuminants, so that different colorimetric parameter conversion and color panel calculation from UV–Vis–NIR spectrum can be selected with different combinations based on people's preference. The user guide of the excel template can be found in Appendix 4. The detailed calculation procedures and formulae used for the excel template can be found in Appendix 5. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03612317
Volume :
47
Issue :
5
Database :
Academic Search Index
Journal :
Color Research & Application
Publication Type :
Academic Journal
Accession number :
158529413
Full Text :
https://doi.org/10.1002/col.22789