Influence of Heat Treatment on the Color Change of Green Tourmaline from Mozambique

Abstract

The objective of this article is to study the influence of heat treatment on the color change of green tourmaline from Mozambique. The 27 samples of green tourmaline were separated into 9 groups, 3 samples in each group. The green tourmaline was heat treatment process via quenching technique at 350, 400, and 450 °C for 6, 12, and 18 h. The Physical properties were examined via the basic gemological instruments. The color was analyzed using an image of green tourmaline.

          The results showed that, the specific gravity value of green tourmaline presented between 2.99 and 3.10. The range of refractive index for n_ε and n_ω of green tourmaline was 1.620–1.630 and 1.640–1.644. The color and transparency comparison of green tourmaline samples between before and after heat treatment, it was found that the color was unchanged but the transparency was increased in most green tourmaline samples after heat treatment.