Beryllium-Diffused Treatment Blue Sapphires with Blue Body Colour

QI LI-jian 1 £¬ C.G.Zeng 2
( 1.Tongke Gemological Institut e£¬ Tongji Universit y£¬Shanghai 200092,China£»
2.Nan Yang Gemological Institut e£¬Singapore 228208£¬ Singapore )


Abstract: A type of beryllium-diffused treatment sapphire with blue or light blue body color has recently appeared on gem markets. The chemical composition, Raman spectrum and the characteristics of UV-NIS absorption spectrum of 50 beryllium-diffused treatment sapphires are investigated by using EPMA, LA-ICP-MS, Laser Raman spectrometer and micro-optical fibre spectrometer. The testing and research reasults show that the minimum mass percent of beryllium is 5.28¡Á10-6 % and the maximum is 17.51¡Á10-6 % and the average is 8.74¡Á10-6 % in the Beryllium-diffused treatment sapphire samples. Generally, the samples contains all forms of baddeleyite melting or pseudomorph inclusion. Because of d£­d electron transition in the Fe3+ion, the absorption spectrum band a (377nm¡¢386nm¡¢451nm£©of the samples is formed. With the high temperature, the beryllium-diffused and induced vacancy color center may result in the blue colour of sapphire.

Keywords: beryllium-diffused treatment blue sapphire; UV-NIS absorption spectrum; LA-ICP-MS analysis; colored mechanism.

*Published in Journal of Gems and Gemmology, 2008, Vol 10, No.1, page 1-4.