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What Enhancements Can Be Made To A Topaz?

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Several varieties of topaz are typically enhanced. Most common is the combination irradiation and heat treatment that produces the blue topaz. For this treatment, colorless topaz is irradiated, which turns it brown. The stone is then heat treated, which turns it blue. While the brown color is generally unstable and will fade with prolonged exposure to sunlight, the blue color is generally stable under normal wearing conditions.

There are three main flavors. The sky blue is produced by gamma rays, the deeper Swiss and London blues are produced by high-energy electrons or nuclear radiation. In the London blues 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 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. This layer is extremely thin.

Some topaz is coated with metallic oxides, similar to the coatings on camera lenses. This coating produces various colors and rainbow-like reflections, but the coatings are easily scratched. The material is marketed under the name rainbow topaz.

Next Page: What Is The Best Lighting And Cut For A Topaz?

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