What is a counterfeit coin or bar?
Counterfeits range from crude plated fakes to sophisticated tungsten-filled bars, tungsten's density is close to gold's, so even weight checks can pass. Popular products like Gold Eagles and one-ounce bars are the usual targets because they're the easiest to sell.
The fakes overwhelmingly enter circulation through private sales and online marketplaces, not through the professional dealer channel, where inventory is verified at intake.
Why is the dealer your main defense?
Because verification equipment, density testers, XRF analyzers, ultrasonic gauges, lives in the trade. An established dealer tests incoming inventory and stands behind what it sells; a stranger on a marketplace offers neither.
Sealed assay packaging on bars adds a second layer: tamper-evident cards with serial numbers are far harder to fake convincingly than loose metal.
How do counterfeits show up in practice?
The pattern is a price slightly too good, from a seller with no storefront, no history, and no written invoice. Paying market price through a verifiable dealer costs a few percent; it is the cheapest authentication service in the world.