Topaz Enhancements loose sale price & Topaz Gemstone Information
As previously mentioned, several varieties of topaz are typically enhanced. Most common is the combination irradiation/heat treatment that produces blue topaz. For this treatment, colorless topazis irradiated, turning it brown. The stone is then heat treated, which turns it blue. While the brown color is generally unstable, fading with prolonged exposure to sunlight, the blue color is generally stable under normal wearing conditions. There are three main flavors. The first, a “sky” blue, is produced by gamma rays (cobalt 60). Deeper “Swiss (a.k.a. ‘windex’) ” and “London” blues are produced by high-energy electrons (cyclotron) or nuclear radiation. In the latter case, the stones must be allowed to cool down to safe levels of radioactivity before being sold. This typically takes a few months to as much as two years.
Another treatment seen on occasion with topaz is bulk diffusion, where stones are heated for long periods surrounded by cobalt. This drives the cobalt into a thin layer at the surface, turning it green to blue. The layer is extremely thin.
Finally, some topaz is coated with metallic oxides, similar to the coatings on camera lenses. This produces various colors and rainbow-like reflections, but the coatings are easily scratched. The material has been marketed under the name “rainbow” topaz.
SwissGemShop - Loose Precious & Semi Precious Gemstones - Gemstone at sale price in Jewelry quality. A lot of Gem information, learn about Gemstones !
Swiss Gem Shop loose Gemstone at Sale price and Gemstone Information