According to Bangkok gemologists, hundreds of dangerously radio-active gemstones are circulating in the Asian markets and some have even found their way into finished jewellery. Tests conducted by radiologists in the Thai capital have revealed radiation levels in some stones were more than 50 times the us safety limit. Experts warn that these jewellery could lead to cancer.

The Bangkok-based Centre from Gemstone Test-ing in a recent warning said that it was likely that these stones may have been bombarded with neutrons in a nuclear reactor. Experts say that a semi-precious stone called cat's eye, which have been irradiated to change their colour from yellow - a colour that gives them a value of -a few hundred us dollars per carat - to an unusual chocolate hue priced at thousands of dollars per carat also has high radioactivity.

A 30-carat radioactive cat's eye set with diamonds in a finished ring was recently discovered at a jewellery fair in Hong Kong. "When it was placed in front of a Geiger counter we literally leapt back," said Jon McDonald, an editor at a local jewellery media firm who witnessed the ring being tested. "The machine was just screeching every time the ring went near it," he said.