Gem cutting, treatment and pigments of gems from South of Torud

The area that contains studied gemstones is located in 19 km South of Torud and 135 kilometer Southeast of Damghan. The quickest and most cost-effective processing method for gemstones in this area is using grind discs in the abrasion and forming stage with the 120 mesh and dry method in polishing stage. The concentration of iron oxide and the presence of calcite and clay minerals made the variation of colors in Turod jasperits. Also Based on ICP-OES analysis, the color of chrysoprases could be related to presence of Ni, pinkish orange agates is due to Fe, Co, Mn and V; and gray colors in agates are related to Cr and Ti. For coloring treatment of yellow agates, cream jasperits, blood stones and opals, heating is the best method. Gems with the texture of micro-spherulitic and micro-variolitic are the most susceptible ones for coloring with chemical method.