In the EU and most other countries it is 74 Bq/gram, a small fraction of the background radiation that everyone is exposed to every day. In the United States, the standard for release and import of blue topaz is 0.4 nanoCuries per gram for a number of isotopes, the rough equivalent of 14.8 Bq/gram. National regulations around the world control the release of gems and other material from irradiation facilities to ensure that it meets safety standards.

The gems are usually cut before they are treated. The colorless topaz used in the process is mined in Brazil, Sri Lanka, Nigeria, and China. But over the years as the process was perfected and production grew, it became surprisingly affordable. Initially, it was very expensive because it was so unusual. Soon the new treated gem was introduced to the market. Experiments with topaz showed that a stable blue color could be induced in colorless topaz or white topaz by irradiating it and then heating it. Scientists researching how color occurs in minerals discovered that natural radiation in rocks in the ground creates the color in many crystals, like zircon and green diamonds. The story of blue topaz is a story of alchemy. Virtually all of the blue topaz on the market today has treated color. Imperial topaz and pink topaz are very rare and valuable in fine qualities.īlue was once the rarest color of topaz, but today it is the most common, thanks to a stable color enhancement process developed in the 1970s. Topaz is known for yellow topaz, golden topaz, brown smoky topaz, sherry red imperial topaz and a few pure pink topaz gemstones. Eventually this name was used to describe the mineral topaz in particular. In ancient times, the name topaz referred to yellow gems.

Topaz clarity store