Pakistan, pink topaz, gems

Gübelin describes gem-quality rose to pink topaz from the Katlang area, northeast of Peshawar, Pakistan. The crystals are well developed and occur together with colorless and brown topaz. Gemological examination gave refractive indices of approximately 1.629–1.642, birefringence 0.009–0.011, and specific gravity 3.515–3.53. The stones show yellow, purple, and lilac-to-violet pleochroism and weak dark-red fluorescence under long-wave ultraviolet radiation. Chemical analysis showed small amounts of chromium and vanadium, with Cr³⁺ principally responsible for the pink coloration. Characteristic internal features include two-phase inclusions and parallel needle-like growth features. The article contains 17 color illustrations.