It looks like any jewelry store: long, brightly lit glass cases sparkle with gold watches, bracelets, and rings.
At the rear of the salesroom here, though, sits irradiation expert Harry Nieman. He slides a small brown packet from his desk drawer. ''I've got to send this one off,'' he remarks, his opened hand revealing a brilliant, 7 3/4-carat diamond that stuns the eye with its blue-green color.
That color, rare for a diamond, is not the work of Mother Nature. It's the work of Mr. Nieman's company, Nu-Age Products, which is in the business of enhancing the color of gemstones through a man-made process. The stone, worth about $15,000 before treatment, would now be worth about $20,000.
Each year, at commercial and university facilities around the world, millions of dollars worth of gems are subjected to high levels of radiation. The result is rarities like canary-yellow diamonds and azure-blue topaz - at relatively reasonable prices.
But recently, the dangers of this atomic age technology were revealed: A batch of gemstones from Brazil was found to be radioactive.
George Rossman, associate professor of mineralogy at the California Institute of Technology, examined the contaminated lot and found that ''they were quite noticeably radioactive.'' Tests proved that some of the semiprecious stones exhibited radiation levels 60 percent above normal background levels. Although the danger of wearing such a stone (none has ever gotten to the retail level) is a topic of dispute, Dr. Rossman says a prudent person would avoid them.
Irradiation, as it's practiced in the US, is safe, says Rossman. The two processes used - gamma ray and electron beam - are tightly controlled and are not conducted at high enough energy levels to produce materials with significant radioactive qualities.