Look for hallmarks. All authentic gold bars and coins have a hallmark stamp that indicates their purity. This stamp is a guarantee from a reputable manufacturer that the gold is 100% pure.

The buyer's only tip-off may be that the price is simply too good to be true, said Schechter. A real gold coin will sell for the spot gold price, plus a $50 to $60 markup, he said.

'Fake' Gold Rush coin declared real: 'It's like finding an original Picasso at a garage sale' By Amy Graff, Senior News Editor Updated April 25, 2018 4:26 p.m.