Affiliation:
1. School of Gemology, China University of Geosciences, Beijing 100083, China
2. Wuzhou Gemstone Vocational School, Wuzhou 543002, China
Abstract
The chemical composition and spectra of rubies heat-treated with high temperatures (above 1200 °C) from Madagascar, Mozambique and Tanzania were analyzed by electron microprobe, LA-ICP-MS, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-VIS spectroscopy. Compared with untreated rubies, the red hue of treated ruby intensifies while its blue tint diminishes, leading to increased cracks. The infrared spectra exhibit a distinct absorption peak at 3738 cm−1, attributed to water because of thermal treatment. After heat treatment, the absorption intensity decreases. Ultraviolet radiation reveals an enhancement in the electron transition of Cr3+ and ion transition of Fe3+ and Fe2+, with a shift towards shorter wavelengths observed in the absorption bandwidth. These can be utilized to indicate the basis of ruby identification through heat treatment.
Funder
the National Innovation Experiment Program for University Students
Subject
Inorganic Chemistry,Condensed Matter Physics,General Materials Science,General Chemical Engineering
Reference42 articles.
1. Laser treatment of colorless natural and synthetic corundum;Kim;J. Gemmol.,2012
2. N and Cr ion implantation of natural ruby surfaces and their characterization;Rao;Nucl. Instrum. Methods Phys. Res. Sect. B,2016
3. The market for colored gemstones: Understanding supply chains, challenges and opportunities in the ruby market;Rondeau;Resour. Policy,2021
4. The market for heat-treated rubies: The double-edged sword of transparency and consumer perceptions in the gem industry;Palke;Resour. Policy,2019
5. A Canary In The Ruby Mine: Low-Temperature Heat Treatment Experiments On Burmese Ruby;Hughes;Gems Gemol.,2022