Chinese manufacturers produce millions of fake coins and bars every year, and they keep getting better at it. These counterfeits show up on eBay, at flea markets, in pawn shops, and occasionally at dealers who do not test their inventory carefully enough. A fake 1 oz gold bar costs about $30 to produce and sells for over $2,000 to a buyer who does not know what to look for.
Pirate Treasure documents specific counterfeits (fake Silver Eagles, replica Morgan dollars, counterfeit PAMP Suisse bars, and dozens of others), explains the telltale flaws, and covers the tools and techniques that catch fakes before they cost you money. Education is the best defence.