Citation: | LIU Yue, PEI Jingcheng, LAI Xiaojing. Gemmological and Spectroscopic Characteristics of Synthetic Alexandrite by the Horizontally Oriented Crystallisation Method[J]. Journal of Gems & Gemmology, 2024, 26(4): 59-68. DOI: 10.15964/j.cnki.027jgg.2024.04.007 |
Cumently, the market is dominated by synthetic alexandrite synthesized by the czochralski method, while the synthetic alexandrite synthesized by the Horizontally Oriented Crystallisation (HOC) method is relatively rare, and the study of its gemmological and spectroscopic characteristics still needs to be supplemented. In this paper, 8 synthetic alexandrite by HOC method from a Russian manufacturer were selected as the research objects and tested and analyzed using conventional gemmological instruments such as refractometers, laser-ablation inductively coupled plasma mass spectrometer (LA-ICP-MS), energy dispersive X-ray fluorescence spectrometer (EDXRF), UV-Vis spectrometer, fluorescence spectrometer, Raman spectrometer, and Fourier transform infrared (FTIR) spectrometer, to explore its inclusion characteristics, trace elements compositions, infrared spectrum, UV-Vis spectrum, fluorescence spectrum, and other characteristics to dirstinguish it from natural alexandrite. The magnified observation results show that the typical inclusions of the synthetic alexandrite samples by HOC method are a large number of oriented elongated voids and clustered metal inclusions. Chemical composition tests show the presence of the colour-causing elements Cr and V. The Cr content is higher than that of natural alexandrite. Fe element content is very low; the content of Mg, Ti, Ga and other elements are lower than the natural alexandrite, with unusual high Mo content, presumably due to the Mo crucible residue. UV-Vis spectrometer test results show a typical chromium spectrum, with two broad absorption bands in the orange-yellow and violet regions, shoulder peaks at 645 nm and 656 nm, and a weak absorption peak at 680 nm. Three-dimensional fluorescence test concluded that HOC method synthetic alexandrite has strong fluorescence peaks at 678 nm and 680 nm, and weak fluorescence peaks at 690 nm and 696 nm, which are all caused by Cr element, and does not have the luminescence center at 460-550 nm caused by Ti and O element in natural alexandrite. The infrared absorption spectrum shows that it does not have the absorption peaks at 2 160 cm-1 and 2 402 cm-1, which are unique to natural alexandrite, and there is no obvious water related absorption between 3 000-3 500 cm-1.
[1] |
罗红宇, 彭明生, 黄宇营, 等. 金绿宝石和变石中的微量元素研究[J]. 矿物学报, 2006, 26(1): 77-83.
Luo H Y, Peng M S, Huang Y Y, et al. Study on the trace elements in chrysoberyl and alexandrite by SRXRF microprobe techniques[J]. Acta Mineralogica Sinica, 2006, 26(1): 77-83. (in Chinese)
|
[2] |
张蓓莉. 系统宝石学[M]. 2版. 北京: 地质出版社, 2006.
Zhang B L. Systematic gemmology[M]. 2nd edition. Beijing: Geological Press, 2006. (in Chinese)
|
[3] |
Sun Z, Palke A C, Muyal J, et al. Geographic origin determination of alexandrite[J]. Gems & Gemmology, 2019, 55(4): 660-681.
|
[4] |
Malsy A, Armbruster T. Synthetic alexandrite-growth methods and their analytical fingerprints[J]. European Journal of Mineralogy, 2012, 24(1): 153-162. doi: 10.1127/0935-1221/2012/0024-2181
|
[5] |
Schmetzer K, Bernhardt H. Synthetic alexandrites grown by the HOC method in Russia[J]. The Journal of Gemmology, 2013, 33(5-6): 113-129.
|
[6] |
罗红宇, 彭明生, 廖尚宜, 等. 金绿宝石和变石的呈色机理[J]. 现代地质, 2005, 19(3): 355-360.
Luo H Y, Peng M S, Liao S Y, et al. Mechanism of chrysoberyl and alexandrite color[J]. Geoscience, 2005, 19(3): 355-360. (in Chinese)
|
[7] |
杨如增, 李敏捷, 陈建. 合成变石的宝石学特征及紫外-可见光吸收光谱分析[J]. 宝石和宝石学杂志(中英文), 2007, 9(4): 7-10.
Yang R Z, Li M J, Chen J. Analysis on gemmological characteristics and ultraviolet-visible spectrum of synthetic alexandrite[J]. Journal of Gems & Gemmology, 2007, 9(4): 7-10. (in Chinese)
|
[8] |
罗红宇. 金绿宝石和变石的矿物谱学研究及其应用[D]. 珠海: 中山大学, 2006.
Luo H Y. Mineralogical spectroscopy of chrysoberyl, alexandrite and their applications[D]. Zhuhai: Sun Yat-sen University, 2006. (in Chinese)
|
[9] |
李立平, 业冬. 铬和钒在宝石变色效应中的作用[J]. 宝石和宝石学杂志(中英文), 2003, 5(4): 17-21.
Li L P, Ye D. Role of Cr and V in colour change effect of gemstones[J]. Journal of Gems & Gemmology, 2003, 5(4): 17-21. (in Chinese)
|
[10] |
李贺, 祖恩东, 于杰, 等. 含铁宝石的紫外-可见光光谱特征研究与计算[J]. 广西轻工业, 2009, 25(11): 12-13.
Li H, Zu E D, Yu J, et al. Characterization and calculation of UV-Vis spectra of iron-bearing gemstones[J]. Guangxi Journal of Light Industry, 2009, 25(11): 12-13. (in Chinese)
|
[11] |
Gaft M, Reisfeld R, Panczer G. Modern luminescence spectroscopy of minerals and materials[M]. 2nd edition. Switzerland: Springer International Publishing, 2015.
|
[12] |
Stoclzton C M, Kane R E. The distinction of natural from synthetic alexandrite by infrared spectroscopy[J]. Gems & Gemmology, 1988, 24(1): 44-46.
|
[13] |
翁诗甫. 傅里叶变换红外光谱分析[M]. 3版. 北京: 化学工业出版社, 2016.
Weng S F. Fourier transform infrared spectral analysis[M]. 3rd edition. Beijing: Chemical Industry Press, 2016. (in Chinese)
|
[14] |
Gao Y, Li X, Cheng Y, et al. Gemological, spectral and chemical features of canary yellow chrysoberyl[J]. Crystals, 2023, 13(11): 1 580.
|
[15] |
Schmetzer K, Pesetti A, Fvledenbach O, et al. Russian flux-grown synthetic alexandrite[J]. Gems & Gemmology, 2012, 32(3): 186-202.
|
[16] |
Powell R C, Xi L, Gang X, et al. Spectroscopic properties of alexandrite crystals[J]. Physical Review B, 1985, 32(5): 2 788.
|
[17] |
Ollier N, Fuchs Y, Cavani O, et al. Influence of impurities on Cr3+ luminescence properties in Brazilian emerald and alexandrite[J]. European Journal of Mineralogy, 2015, 27(6): 783-792.
|
[18] |
Nassau K. The physics and chemistry of color: The fifteen causes of color[M]. New York: Wiley, 2001.
|