For safety reasons check your irradiated blue topaz jewelry. Topaz is mined as a white colorless gem. It is then irradiated to make it blue. The deeper the color, the stronger and longer the irradiation. Normally these blue topaz are to be left alone for a few years so that they can cool off or give off their radiation in a vault before they are sold to be made into jewelry. Unfortunately , in the 90's, there were reports of gem dealers in Asia selling blue topaz to merchants before they had properly cooled off. As the regulations stand now, they mostly concern blue topaz in the darker shades. Your local jeweler may have a Geiger counter and be able to check your blue topaz jewelry for you.