Irradiation is secretive, complex business

The business of gemstone irradiation - although rewarding - is risky, highly secretive, and complex.

For a gem owner who wants a vibrant blue or glittering yellow stone, the path to success is fraught with difficulty. Much depends on the knowledge of experts like Harry Nieman, who, with more than 20 years experience, can determine the color that will be produced in a stone by a certain dose of radiation.

Diamond irradiation expert Marcus Fuchs, head of Chroma Gem in New York, says that often the value of a gemstone will decrease after irradiation. ''Sometimes diamonds contain minerals that will cause them to turn brown.''

The irradiation expert must also choose the proper process - gamma ray or electron beam - and then take the stone to the correct irradiation facility. ''Every facility does something different to a stone,'' says Mr. Nieman.

Because of the large variability in each stone and radiation facility, the experienced irradiation expert is irreplaceable. Much of his invaluable knowledge is veiled in secrecy. Says Nieman, ''Every time I go to irradiate a diamond [at one of the facilities he uses] I change my route. Many times I'm followed, and not by crooks, but by other members of the irradiation industry.''

Approached by gemstone brokers, cutters, designers, and retailers, Nieman says that sometimes he is asked to meet potential customers in secret hotel rooms. ''They bring in suitcases and bags full of topaz and other stones that you couldn't lift.''

But Nieman says he hasn't gotten wealthy from the business. He rarely markets the stones he has produced, doing it instead as a service. ''But I enjoy every minute of it.''