There is a 3-carat diamond waiting for Tammy Borg at a shop on Chicago’s historic Jewelers Row, one that’s so big it’ll nearly cover the width of her finger.

She and her soon-to-be fiance spent weeks hunting for the perfect diamond for her engagement ring, and finally found it at Mon Ami Jewelry. The diamond has a few flaws, Borg said, but to her, it’s perfectly imperfect.

“I would’ve never considered anything other than (a natural diamond),” she said.

Jewelers say there is a growing acceptance of synthetic diamonds, but most buyers still seem devoted to natural stones.

Technology has allowed man-made diamonds to become so similar to mined diamonds that the stones are finding their way into the market, for better or worse, with some budget-conscious shoppers requesting them as a cheaper alternative.

Their rise has left diamond sellers concerned that synthetics could creep into their inventory unannounced, especially during the holiday shopping season, one of the year’s busiest times for jewelry sales.

No jeweler wants to be the one that sells a client a man-made diamond the jeweler thought was natural, especially when customers — often inexperienced in diamonds — rely on the jewelers to educate them.

It hasn’t become a problem yet, but the tenants along Chicago’s Jewelers Row want to be ready when it does.

Windy City Diamonds, for example, bought its own machine to test for synthetics — and such machines can cost thousands. Others are relying on labs to do the testing for them.

The concern is triggering an effect similar to the one seen with blood diamonds.

Just as jewelers once had to secure their supply chains against stones coming from war-torn areas — so-called blood diamonds sold to finance insurgencies or warlords — now they’re guarding themselves against nefarious sources that could slip man-made diamonds into the supply.

“We always want to know the lineage of our diamonds,” said Anand Sheth, owner of Mon Ami Jewelry.

Some worry that pawnshops won’t pay much for them, and that few will be eager to inherit their grandmother’s synthetic diamond rings. The market knows that diamonds are forever, but it’s not quite sure yet what happens when those diamonds are man-made.

“Where’s the value in something you can make a billion of?” said Garry Zimmerman, co-owner of Windy City Diamonds. “I can’t in good conscience sell something that I think is intrinsically going to lose its value.”

In November, Zimmerman ordered a machine to test for synthetics from De Beers, one of the world’s largest diamond companies. He’ll be able to put a scoop of small, loose diamonds on the machine’s tray, switch it on and test the stones with a UV light. If the glow lingers on the stones once the light is off, that’s a red flag — phosphorescent glow can indicate a diamond is treated or man-made.

It’s those small, usually less than one-quarter carat stones that could pose the biggest problem, said Eitan Tashey, education coordinator at the Professional Gem Sciences Laboratory on Jewelers Row. Larger stones are tested and certified at labs, like his or GIA’s, but the little, more difficult to handle diamonds don’t as often get checked to make sure they’re natural.

Professional Gem Sciences has seen an increase in requests to test diamonds, as concern over the synthetics spreads, Tashey said. The lab’s machine shoots a beam of light through diamonds, and flags a stone as potentially man-made based on how the light moves through it. The experts then must get behind their microscopes and use other technology to examine further.

The lab’s walls are covered with charts showing the minute differences between real and man-made stones, and shelves are full of books with diamonds on the covers.

Tashey lays out a few yellow and orange diamonds and runs a magnet over them. The stones quickly hug the magnet — behavior unheard of from a mined diamond. But those gems were made four or five years ago, he says, unveiling a 1.09-carat white diamond manufactured within the last year. That one won’t budge when a magnet is nearby.

“In some ways it’s like an arms race,” Tashey said. “As soon as somebody figures out there is a way to tell it’s not natural, the companies go back and fix it because they’re trying to perfect the product.”

Some jewelers aren’t yet prepared to protect themselves and their customers against the potential pitfalls synthetic diamonds could create in the market, Tashey said.

His mother Myriam Tashey, vice president of Professional Gem Sciences, agreed. It’s only a matter of time before a customer ends up with an undisclosed man-made diamond, she said.

“It’s not if, just the question is when,” she said. “People are going to lose money.”

— Chicago Tribune