Staff Reporter

GUNTUR: Precious stones like rubies and saphires, which could be modified by using diffusion-controlled chemical reactions, have greater commercial value, says M.D. Sastry of Gemmological Institute of India.

Addressing an international seminar on ‘Science and technology of glass materials’ being conducted on the premises of Nagarjuna University here on Tuesday, he said that chemical reactions triggered in precious stones at high temperatures of around 1800-1900 Celsius would induce inter valent charge transfer among the impurities.

The most common practice of colour modification was diffusion of Beryllium by heating Corundrum crystal with chrysoberyl containing fluxes.

Among the other presentations there were made on the second day were ‘Photo-luminescence in glasses and glass ceramics’ by Doris Ehrt from Germany, ‘Glass matrices for vitrification of radioactive waste – an update on R&D efforts’ by Kanwar Raj, ‘Optical spectroscopy study of local structure of rare earth ions in fluorozirconate glasses by temperature-induced and pressure-induced phase transition processes’ by Victor Lavin and ‘Thermophysical and Structural studies on some glass-ceramics and role of nano size crystals’ by G.P. Kothiyal.

Poster session

The presentations were followed by poster sessions from various scientists.