Sara Patterson-Robert can tell just by a glint in the eye when she's being swindled into buying fake gold.

She's had some shady customers at her Edmonton store over the years, but she's never been duped.

She knows, not all that glitters is gold.

Fake gold

Edmonton police are warning the public about counterfeit gold bars being sold in the city. (Supplied)

"It's fairly obvious when they know that it's a fake, by their reaction," said Patterson-Robert, the manager of Edmonton Gold Buyers in the Strathcona neighbourhood.

"Some people, when I tell them that I need to take [the gold bar] from its packaging to test it, they take it and run."

Patterson-Robert is not alone. Edmonton police are warning businesses to watch out for phony gold.

In a Monday afternoon news conference, investigators said more than 20 merchants and individuals across the city had been tricked into buying the counterfeit bar in recent months.

Though the bars are being sold for anywhere between $300 and $800 each, they're basically worthless, valued at less than a dollar a piece. Store merchants are usually the primary target but police are seeing the bars sold online through websites such as Kijiji.

Patterson-Robert says fakes have always plagued the industry but the bogus bars are looking more convincing.

To the naked eye, the bars look legitimate. The packaging is professional, and they are usually plated with gold so even the sharpest-eyed jeweler could be fooled.

Patterson-Robert relies on a special density machine to test the karat of each bar and ensure the product is legitimate.

"The quality of the fake gold has gotten better and less easy to detect," said Patterson-Robert in an interview with CBC Radio's Edmonton AM. "Back in the day, it used to be really obvious but now you have to actually take it out of its packaging and test it to know.

"The majority of the fake gold bars are plated in gold in case someone does a scratch test on it," she said, noting that they're actually made of copper or tungsten.

'We live in a buyer beware market'

Not every customer Patterson-Robert has encountered with fake bullion is aware that they've been fooled. Some have unwittingly bought the bad gold online or acquired it through acquaintances. Her most recent fake came into the shop last month.

She says consumers should be aware of the current market value for gold and only do business with reputable dealers.

"We live in a buyer beware market. If something seems too good to be true, it probably is," she said.

"Check out the spot price of gold, and if someone is selling it for half of that price, it's probably fake." 

'Everybody has a theory when it comes to gold' 

Despite the bogus bars, Patterson-Robert said business is booming. Gold is a safe investment. It retains its value and prices continue to rise over time.

There will always be people who fall for the lure of gold. And from what she's seen the eccentric are especially susceptible to gold fever.

"I get a lot of people coming in with really old paper money that's been hiding under their mattress for years. They want something that the government doesn't know about, something they can hold in their hands," she said.

"I spend a lot of time kind of smiling and nodding to people. Everybody has a theory when it comes to gold."

With files from Alex Zabjek