There are 2 telltale signs that a diamond is fake, according to a woman who designs and sells 6-figure engagement rings

Katie Warren/Business Insider

Nicole Wegman, founder and CEO of Ring Concierge, says diamond experts "can tell immediately" if a diamond is fake.

• Nicole Wegman is the founder and CEO of Ring Concierge, a company that designs and sells customized engagement rings ranging from $10,000 to well into the six figures.
• Wegman told Business Insider there are two main ways to spot a fake or synthetic diamond.
• If the stone has too much rainbow reflection or if it just seems dull, it's probably not a real diamond.
• The easiest way to see the difference is to hold it next to a real diamond, Wegman says.

Nobody wants to get duped by a fake - especially when it comes to diamonds.

Nicole Wegman, founder and CEO of Ring Concierge, a company that designs and sells customized engagement rings ranging from $10,000 to well into the six figures, says diamond experts "can tell immediately" if a diamond is fake.

But for those who aren't jewelers or diamond experts, there are two telltale signs that you're looking at a fake diamond.

"Usually there's too much rainbow reflection coming out of a fake diamond," Wegman told Business Insider. "It should be white flashing back at you. A little bit of rainbow."

Katie Warren/Business Insider

Wegman inspects a diamond through a magnifying glass at Ring Concierge's NYC office.

The second tip-off will be the lack of brilliance.

"They usually feel a little dead," Wegman said. "They just don't have the liveliness and the brilliance that you get from a real diamond. I think the easiest way to see the difference is to hold it next to a real diamond. If you have it side by side with a real diamond, you're going to be like, 'There is something just weird about this stone. Something's off.'"

Taylor Lanore, a diamond expert and Ring Concierge's PR director, said you can also sometimes see a "seam" within the stone that will indicate it's not a true diamond.

Of course, Wegman said, you can always bring a questionable stone into a jeweler and they'll be able to tell you "in two seconds" whether it's real or not.