Research On Gemological Characteristics And Enhancement Process Of Rubites From Yunnan Province

Rubies are one of the most precious gems in the world. High-quality rubies is extremely rare on the market and the price is going up.Ruby deposit in Yuanjiang, Yunnan province which was found in the late 1980s, is the best ruby mines in China. It is abundant in reserve and is in non-mining state. The research on this deposit or rubies is not much. In this paper, the characteristics of the ruby deposit and rubies are researched by exploring and studying some geological data, and the genesis of rubies deposits is analyzed.Physical-chemical characteristics were tested and analyzed by EPMA, XRF, SEM and other modern test technology to different types rubies from Yunnan province, such as chemical composition, crystal structure, crystal morphology and micro-morphology, color, transparency, density, cleavage, luminosity and so on. Raman spectroscopy, infrared spectroscopy, and UV-visible absorption spectroscopy were tested and analyzed to rubies from Yunnan province. At the same time, spectra were compared with rubies from different origin. Color-causing elements and coloration mechanism of rubies were discussed by theory of crystal field and quantum theory. Impurity component, polysynthetic twinning, fracture and hole are main factors influencing the transparence of rubies. The results showed that Rubies from Yuanjiang, Yunnan province contain a large quantity of inclusions and low transparency. Main color-causing element is Cr, Fe, Ti, etc. Among these elements, average content of is 0.45%(concentration range 0.03-2.22%). Color shade is directly related to the content of Cr3+, including energy level transitions of 4A2?4T1?4A2?4T2 and 2E?4A2, which cause strong broad absorption band at 407,551nm and 694 nm fluorescence peak. The content of Fe, Ti ions in rubies influences color tones and makes rubies pink or purplish.375,414 and 640cm-1 raman shifts are related to Al-O vibrations, and 1080cm-1 raman shift is related to calcite inclusions. and IR spectra showed 381cm-1?420cm-1 and 647cm-1 characteristic bands of Al2O3.Based on gemmology and coloration mechanism, enhancement process is especial to rubies from Yunnan province, including useful assistant reagents, reasonable experiment process and temperature system for improving color and transparence of rubies. Impurity elements such as Fe, Ti precipitated or changed in valen treated in oxidizing atmosphere at 1480?and for 24hours at constant temperature and used Al(OH)3 or Al(OH)3 and CaCO3 reagants. After the heat treatment, color and transparence of rubies improved. Filling experiments under open atmosphere at 1480?and used Bi2O3 and Al(OH)3 reagants can fill the fracture and hole of rubies effectively.