Up close, there are relatively few differences between natural and created diamonds. To the naked eye, created diamonds are virtually indistinguishable from mined diamonds, but with special equipment, naturally-occurring imperfections called inclusions are visible in most organic diamonds. Like snowflakes, no two diamonds are exactly alike; the degree to which these inclusions are present determine a diamond's clarity. Lab-grown diamonds lack inclusions, however, making them appear more brilliant (read: sparkly)—ideal for shoppers looking for the biggest, blingiest diamond they can afford, but less great if you're concerned about other people questioning its authenticity.

For both retailers and consumers, there's also an ethical concern when it comes to the origins of natural diamonds. About 65% of the world's diamonds are mined in Africa, sometimes in war zones by forced labor, the proceeds of which are often used to fund those wars. In 2003, the diamond industry established the Kimberley Process, a certification system designed to assure consumers that the stones they bought were conflict-­free. While the effort significantly reduced the number of blood diamonds on the market, some sources estimate that as much as 10% of the world's supply today were harvested in unethical circumstances. (The CEO of DPA estimates that figure closer to 1%.) And even in mines outside of war zones, laborers, who are sometimes children, are often poorly compensated for the grueling conditions they endure.

For Tim Castelein, a 26-year-old mechanical engineer, that concern alone was enough to steer him toward lab-grown stones ahead of his engagement. "I'm a pretty environmentally conscious person, and as I learned more about the processes that go into harvesting diamonds, and especially some gemstones... It's hard to get behind that as something I want to fund."

Lab-grown stones might not be a perfect solution to ethical concerns, though. "The claims by some lab-grown diamond producers that their products are transparent, ethical, and eco-friendly have never been proven," according to a DPA spokesperson. "Many are actually produced in Asia using large quantities of fossil fuels with a higher carbon footprint per carat than a natural diamond."Like any industry, though, sustainability practices vary between companies: all the power for ALTR's plants comes from wind turbines.

Shah says that shoppers can generally increase the size of their diamond by 50% when they consider a lab-grown stone: for the same price, one carat becomes one and a half. Of course, not all women want the biggest possible rock on their finger. "At the larger size, I felt like I wouldn't have been able to take compliments well," said Morgan Taylor, a real estate agent in Atlanta. "That seemed excessive."

"I really tried to be convince myself to be into lab-grown, but because there's not a lot of knowledge on it, I knew I would still feel weird about it," said Taylor. "I'd rather have [a diamond with] flaws and know that my diamond was grown in the earth."

Aside from stigma, the other main deterrent is the longterm value of a lab-grown diamond—it's a new product and lacks that "rare" qualifier. But most natural diamonds actually don't fare so well by that measure. "Diamonds are forever"—at least until you leave the jeweler, at which point your shiny new diamond loses over 50% of its value.

"I always tell people, if you really want to invest in luxury, buy a Chanel bag, or Patek watch, or a Birkin bag," not a diamond, said Shah.

Castelein was concerned about potential stigma as well, until he was inspired by a fateful conversation with his grandfather. "Somehow, the ring he got for my grandmother came up," explained Castelein. "He was like, 'I couldn't afford hardly anything, so I just got her this cubic zirconia ring.' He was always planning on replacing the stone, but she was like 'No, this is what our relationship was at that point.' She never questioned it, and now it's a family heirloom."

"In the long run, it's not going to matter, where it ended up coming from. It's going to take on its own significance and importance," said Castelein.