In a small hillock of recrystallized limestone north of Katlang, narrow calcite veins encase pink topaz crystals up to 3 cm long accompanied by larger amounts of reddish brown, tan, and colorless topaz crystals. More than 70,000 ct of gem-quality pink topaz has been reported to date.The refractive indices, optic axial angle, unit-cell dimensions, and density of the topaz are influenced by a partial replacement of fluorine by hydroxyl ions. The color is due to trace elements-principally chromium (Cr3+). Treatment experiments revealed that the color of the brown, tan, and colorless topaz from this source may be improved by irradiation and heat. Weight - 79.1 ctw Natural Raw rough no treatments, no heat, no modifications or enhancements No Heat treatment Topaz is mostly found in yellow color. Pure topaz is transparent and colorless, the impurities causes variations in color. Topaz comes in various colors like yellow, pink, green, purple, orange, and many famous blue tones. Blue Topaz is rare and virtually all Blue topaz stones are heat treated and/or irradiated. The most valuable colors of topaz are the golden orange-yellow type known as'Imperial Topaz'. The deepness of the color with reddish hues adds value to the gem and is very desirable.
Continuous exposure to daylight can fade the yellowish brown colored topaz.