Now, nine times out of 10, people shopping at Saettele Jewelers for an earth-mined diamond leave with a lab-grown one, said Gary Saettele, co-owner of Saettele Jewelers in Town and Country, Missouri, a suburb of St. Louis. Lab-grown diamonds make up about 90% of the store's diamond sales, he said.

"I think it's the way the future is going to be, personally," he said. "The biggest difference is price."

A 2-carat earth-mined diamond sits at about $19,000, while a lab-grown diamond of the same cut, clarity, color and carat size is only $2,100, said Saettele. That's $1,050 a carat versus $10,000 a carat.

Saettele said he assures people who want a "real" diamond that the lab-grown gems are, indeed, the real deal. The Federal Trade Commission even determined lab-grown diamonds were diamonds in 2018.

"Take in vitro fertilization," Saettele said. "Once that child is born, is that a real baby? Once this diamond is harvested it's a real diamond just like that child is a real baby."

Last year, lab-grown diamonds made up more than 17% of the diamond market, according to diamond research analysis agency, Edahn Golan. Sales jumped 38% between 2021 and 2022 and the lab-grown diamond market is expected to reach $20.6 billion by 2032.

Diamond mining practices have become increasingly criticized in recent years, as open-pit and underground mining requires the removal of hundreds of acres of earth to reach raw diamonds far underground. Concerns about working conditions and the exploitation of miners, and the potential for diamond sales being used to finance violent conflicts in war-torn areas, have some consumers looking for alternatives.

"It can be very toxic and very dangerous for those working on it," Saettele said.

Lab-grown diamonds are created in two ways: high-pressure, high-temperature and chemical vapor deposition.

During the high-pressure process, a diamond "seed" is put under high pressures and temperatures similar to what a natural diamond would undergo. In the second, more commonly used process a diamond seed is placed in a chamber with high temperatures and a carbon-rich gas mixture. The gases break down their molecular bonds, which allows carbon layers to build and grow on the seed.

Because the growing process has been perfected, the diamonds are now grown to be as brilliant, clear and white as earth diamonds, jewelers say. And they're significantly less expensive, said Leo Anglo, general manager at Vincent's Jewelers in Creve Coeur, Missouri. Lab-grown diamonds make up 75% of diamond stud earrings sales and about half of the engagement ring sales at the store, he said.

"They can't get much cheaper," Anglo said. "There's no question that lab-grown diamonds have changed the landscape. I think it has opened the door for some millennials to buy."

The lower prices are attractive, Anglo said, but lab-grown diamonds don't hold their monetary value the way natural diamonds do. He said the price of lab-grown diamonds has dropped by half each year. "I think it's a great product. I think it's a great alternative," he said. "But, there's no turning back. It's not like you're going to bring it back and get all your money back."

Anglo said he's had customers on both ends of the spectrum — some just want to get the biggest, best gem possible while others are adamant they buy what they consider the "real" thing.

"Why do people pay way more at a Tiffany where they can get the same thing somewhere else for half the price? Because they want the prestige of buying Tiffany," Anglo said. "Some people are going to want a natural because they're going to want the prestige of knowing they got a natural."