“What we know from experience is the psychological footprint from a nuclear disaster can not only be massive but in many ways greater than the effect of radiation,” Becker said.

Dire warnings of radiation spreading from Japan's embattled Fukushima Daiichi nuclear power plant to deadly effect across Japan, or even to California, are likely overblown, they say.

Also discussed are characters and application of the nuclear radiation sources for the gem colour-enhancement process, and the mechanics and effect of the gem colour induced by radiation.