Blue Topaz — The Irradiated Gemstone

Maureen Conley
Public Affairs Officer

There are a lot of great things about having a November birthday. The heat of summer is over but winter hasn’t set in so the weather can be magnificent. When the leaves are changing, the landscape is even more beautiful than in spring. It is the month of football, first frosts, harvesting the last of the summer vegetable garden, and my favorite holiday, Thanksgiving. But the one thing I never liked about my November birthday was my birthstone—topaz.

topaz 1Orange is just not my favorite color. I was always jealous of my family members, whose stones were so much prettier—amethysts in February, diamonds in April, and sapphires in September. Then one year I received as a gift some earrings with a beautiful blue stone. That was my introduction to blue topaz.

I was so happy to discover there was an alternative to the traditional orange topaz, I never thought to wonder what was behind the blue color. I figured topaz just came in blue, too.

Well it turns out blue topaz can be found in nature but it is very rare. Most blue topaz on the market has been exposed to radiation.

This is no cause for alarm. Irradiated gemstones are not harmful. Because they may be slightly radioactive immediately after their treatment, the NRC regulates the distribution of these products to ensure public health is protected. Any measureable radiation decays away within a couple months. Treated gemstones are set aside and are not sold until the radioactivity falls far below levels that can impact public health.

Distributors of irradiated gemstones must have an NRC license, which requires them to do radiological surveys before selling the gems. Their sophisticated instruments can detect very low levels of radiation. Once the radiation is low enough, no further licensing is required.

topaz 1Topaz is not the only gemstone treated with radiation to change its color. Diamonds, pearls and other gemstones are sometimes irradiated to change their color. In general, the longer stones are exposed to radiation, the deeper and more attractive the color.

Incidentally, not all radiation treatments applied to gemstones make them radioactive. If they are bombarded with neutrons, as in a nuclear reactor or accelerator, trace elements in the stones can become “activated” or radioactive. But gemstones can also be treated using gamma radiation (high-energy photons), which does not make them radioactive.

If your holiday shopping list includes jewelry this year, don’t be afraid of irradiated gemstones. The NRC license ensures they don’t reach the market until they are completely safe.