[youtube]http://www.youtube.com/watch?v=89ATeNy3DIo[/youtube] Video of a fake 100 gram silver bar that was XRF tested as genuine silver. Basically a very heavy silver plate applied to an otherwise low-tech fake bar that was the correct weight. Bar was larger than it should have been, a specific gravity test would have also caught this one. Sample was provided post destructive testing.
I don't sell them, but they are on eBay. Looked at importing a bunch but wasn't much going in terms of a bulk discount.