– When Jeff Griffin read an Internet article four years ago about how Pittsburgh jewelry designer Paul Bierker had created a Star Wars-themed R2D2 engagement ring, he knew he wanted Bierker to make an engagement ring for his girlfriend one day.

The time arrived on April 7 at the grand opening of The Wizarding World of Harry Potter at Universal Studios, Hollywood. While Griffin's fiancée — a huge Harry Potter fan — was participating in a "wand choosing" ceremony, he got down on one knee and presented her with a ring based on the Golden Snitch from the Harry Potter books and films.

The yellow and white gold band was designed to look like wings, symbolizing the prize in the Quidditch game played by wizards in the stories. For the ring's centerpiece, Griffin, 34, of San Leandro, Calif., specifically chose a synthetic one-half carat yellow diamond rather than a natural one.

"My first choice for a gemstone was a lab-grown diamond," he said. "I chose to go with a synthetic diamond for the cool factor.

The imitation diamond industry has existed for years, but until recently the man-made gems tended to be fairly rough quality stones with discolorations and visible flaws. Now the technology has evolved to the point where even the experts need special equipment to tell the difference.

The growing popularity of lab-grown diamonds has led movie star Leonardo DiCaprio and 10 Silicon Valley billionaires to get into the game by investing in a Santa Clara, Calif.-based company called Diamond Foundry. The company claims it can grow hundreds of diamonds that are up to nine carats in just two weeks in a lab.

Lab-grown diamonds are causing quite a stir among the old guard.

Sellers of natural diamonds have expressed concern that consumers could be misled and confused. The latest dust-up between the two camps involves a petition that marketers of man-made gems have made to the Federal Trade Commission that would allow them to describe their merchandise as "cultured" diamonds. Sellers of natural jewelry and gemstones are vehemently opposed.

"I honestly think there is a fear in the market that synthetic diamonds will take a piece of the pie from the natural diamond market," said Bierker, owner of Paul Michael Design, who created the engagement ring for Griffin. Bierker has specialized in creating custom jewelry for the past 20 years. He began selling synthetic diamonds about a year ago. He said more customers have been requesting them.

Diamond industry sources liken the process of creating a lab-grown diamond to growing a plant. You need a seed from another plant for a new one to grow. With lab-grown diamonds, a small slice of a natural diamond is used as the base or seed to grow new layers on top of the crystal until new diamonds are formed. That seed is scraped off and reused to grow new diamonds.

Synthetic diamonds are grown in a reactor that produces intense heat, about 8,000 degrees — about as hot as the outer layer of the sun. Inside the reactor, atoms stack on top of the natural diamond layer by layer until a pure, jewelry-grade diamond is formed.

John King, chief quality officer at the Gemological Institute of America in New York, said, "Diamonds that are grown in a lab have essentially the same chemical properties and physical characteristics of natural diamonds."

"In the 1970s, we saw the first synthetics that were the quality we would see in gems and jewelry," King said. "Over decades with advances in technology, the quality and speed of producing them has increased."

Danny Baruch, vice president of American Grown Diamonds, a wholesale synthetic diamond distributor that sells to more than 150 retailers throughout the country, said the company's sales are growing month over month as more people become aware of the product.