The ancient Egyptians created them. King Tut's tomb was adorned with them. Even the Duchess of Windsor secretly kept them.

Simulated stones have a long and colorful history in the jewelry world, imitating the rare and beautiful gems that took nature years to produce.

Most people prefer the real thing, but affordable look-alikes, including lab-grown synthetics, have found a comfortable niche in the gem industry. That's all right with purveyors of fine jewels so long as they're not passed off as the genuine article.

"Fakes and phonies are as ancient as gems themselves," said Antoinette Matlins, a gem expert and author of "Jewelry and Gems: The Buying Guide."

Matlins says counterfeiting was going on 2,000 years ago, although technological advances have made it tougher to detect today.

While simulated stones have been around for centuries--Egyptians created imitation turquoise and adorned old Tut's tomb with blue glass "gems"--commercial production of synthetic precious gemstones didn't come about until the turn of this century.

Scientists have made great strides in creating stones that so closely resemble the real thing that some dealers have been fooled. They've also figured out ways to greatly enhance the look of real gems, like fracture filling, a relatively new process in which a liquid glass is used to fill in surface cracks in diamonds and colored gemstones.

"What normally happens, when you have a brand-new technique or treatment (in jewelry production), there's a lag time between the introduction of the product and awareness," by the overall industry, Matlins said.

She said it's often during that time that unscrupulous individuals will try to take advantage of reputable dealers, claiming for instance, that a well-made synthetic ruby is a rare and expensive natural ruby. When cubic zirconias were introduced, a few dealers mistook them for real diamonds, she added.

"The vast majority (of jewelry dealers) are honest. But the vast majority are not gemologists, so they can buy into a deception unknowingly," Matlins said.

It's important, therefore, for consumers to make all major purchases contingent upon verification by gem-testing labs like the Gemological Institute of America. Some jewelers may have had the tests conducted already.