Value Addition of Quartz Gemstones through Gamma Irradiation

Abstract

Color enhancement of gemstones through gamma irradiation is an established technology throughout the world. By value addition, the traders earned manifold prices to these colorless stones as compared to the fresh ones. For the color enhancement of these semi-precious stones, optimized doses of irradiations are required. To get the optical properties of the stones and to investigate the crystal lattice and chemical composition, X-Ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques were applied in this study. The colorless pure samples of quartzes were collected and subjected to gamma irradiation doses up to 1.5 M rad or 15mGy for valuable colors of the samples. In XRD analysis of the samples, small peaks were observed in the pattern after irradiation indicating change in the phase of SiO_2. The elemental analysis of fresh and irradiated sample was performed by EDX analysis to investigate the color change in quartz. Stability of the colored quartz samples was determined up to 200 ⁰C by thermal treatment. After irradiation the induction of radioactivity was checked with the help of radiation detector. It was observed that no radioactivity had been found in the irradiated samples of quartz.

Keywords: Quartz; irradiation; coloration. value addition, XRD