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Blumentritt, F. & Fritsch, E. (2022) Photochromism and Photochromic Gems: A Review and Some New Data (Part 2). Journal of Gemmology, 38 80–92.
Added by: Richard Baschera (2022-10-28 09:26:26) Last edited by: Richard Baschera (2022-10-28 09:26:59) |
| Type de référence: Article DOI: 10.15506/JoG.2022.38.1.80 Numéro d'identification (ISBN etc.): 1355-4565 Clé BibTeX: Blumentritt2022 Voir tous les détails bibliographiques  |
Catégories: MIOPS Créateurs: Blumentritt, Fritsch Collection: Journal of Gemmology |
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Part 2 of this article reports on photochromism in diamond, corundum and baryte. Diamond provides the greatest number of photochromic behaviours for a single gem species, with five varieties, only one of which is related to the well-known silicon-vacancy colour centre. The photochromic behaviour of chameleon (green/yellow) diamonds is probably related to various impurities (N, H, Ni and possibly O). Three of the other photochromic diamond varieties involve the addition of brown colour, but they are unlikely to originate from the exact same mechanism. For corundum, we propose that yellow-orange photochromism is linked to an electron moving in and out of a hole centre. For baryte, doubt remains with regard to published descriptions of the yellow-to-blue change in colour with exposure to sunlight, but involvement of sulphur is a possibility for this sulphate mineral. In general, since photochromism modifies the colours of gems, and since the effect is reversible, it is important for the gemmological community to be aware of its potential influence on colour grading.
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