The coin collectors are having a horrible problem with this.
It is legal to counterfiet coins if you mark it somewhere with
the word 'copy'... However, you can buy high dollar coin copies
that are getting more convincing everyday, from China, and you
can specify that they not mark it as a copy. Of course all the
ads and
ebay auctions have pictures of coins that are marked,
but anyone knows you can contact the seller to leave it off.
Then the coins (unmarked) show up on
ebay almost immediately,
portrayed as 'real'. You can even look at the sellers' purchase
history and trace many of the coins right back to the auction
where the now seller bought them. It's crazy.
I'd hate to see the same thing happen to stamps, but these guys
are pros at finding a way to make a quick buck off Americans.
(and others, of course)