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Enhancement of raw semi-precious gemstones as a special type of processing of nonmetallic mineral resources

Raw semi-precious gemstones, widely used in the jewelry industry, undergo certain stages of processing as ore mineral resources. These stages are cutting, power-tool treatment, chemical etching, etc. However, the most important stage of raw semi-precious gemstone treatment is enhancement–in the authors’ opinion, this is a special form of processing of nonmetallics, aimed at their appreciation and at improvement of their qualities and running characteristics. An example of such approach is the sequential thermal treatment of brown chromiferous andradites in the oxidizing (duration of 45–60 min, T of 760 °С, heating rate of 6–10 °С/min) and reducing (duration of 120 min, T of 820 °С, heating rate of 6–10 °С/min) media. Such treatment allows producing demantoid garnets of almost standard green color saturation owing to suppression of color centers Ti3+ and enhancement of Cr3+, thereby raising the cost of the initial material by hundreds of times. Alongside with this example, the article describes the other types of treatment such as soaking of porous turquoise and radiation of fade-colored sapphires, which also can be assumed as the special types of processing of nonmetallic minerals. In this fashion, treatment of the initial raw semi-special gemstones using different methods of improvement enhances decorative and running characteristics of the material, and raises its cost. From this point of view, enhancement offers process solutions in the field of treatment of raw semi-precious gemstones and can be a special type of their processing.

Keywords: enhancement, crystal raw material processing, raw semi-precious gemstones, thermal treatment, demantoid garnet, turquoise, sapphires, radiation.
For citation:

Akhmetshin E. A., Klimkin I. A., Plechov P. Yu., Petrova O. B. Enhancement of raw semi-precious gemstones as a special type of processing of nonmetallic mineral resources . MIAB. Mining Inf. Anal. Bull. 2025;(6):21-39. [In Russ]. DOI: 10.25018/0236_1493_2025_6_0_21.

Acknowledgements:
Issue number: 6
Year: 2025
Page number: 21-39
ISBN: 0236-1493
UDK: 553.85:553.89:553.823
DOI: 10.25018/0236_1493_2025_6_0_21
Article receipt date: 25.10.2024
Date of review receipt: 24.12.2024
Date of the editorial board′s decision on the article′s publishing: 10.05.2025
About authors:

E.A. Akhmetshin1, Senior Lecturer, e-mail: 4966945@mail.ru,
I.A. Klimkin1,2, Graduate Student; Museum Keeper, e-mail: klimkin.ivan.aleksandrovich@gmail.com,
P.Yu. Plechov2, Dr. Sci. (Geol. Mineral.), Professor of the Russian Academy of Sciences, Director, e-mail: pplechov@gmail.com,
O.B. Petrova1, Dr. Sci. (Chem.), Professor, e-mail: petrova.o.b@muctr.ru, ORCID ID: 0000-0001-7828-1058,
1 D.I. Mendeleev Russian University of Chemical Technology, 125480, Moscow, Russia,
2 A.E. Fersman Mineralogical Museum of the Russian Academy of Sciences, 119071, Moscow, Russia.

 

For contacts:

I.A. Klimkin, e-mail: klimkin.ivan.aleksandrovich@gmail.com.

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