Summer 2008

Coloring of Topaz by Coating and Diffusion Processes: An X-ray Photoemission Study of What Happens Beneath the Surface

Harald Gabasch, Frederik Klauser, Erminald Bertel, and Thomas Rauch

Surface-treated topaz has become a viable alternative to topaz colored by irradiation. Unlike irradiation, which modifies the entire gemstone, coloration by chemical modification is limited to the near-surface region. The treatment techniques are well established, but less is known about how the processes involved create the desired appearance. In this study, X-ray photoemission spectroscopy in combination with sputter depth profiling proved successful in characterizing two fundamentally different coloration mechanisms of chemically treated topaz: colored coatings and diffusion-induced coloration.

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