Fake US silver Trade Dollars and fake Chinese silver dollars are on the market.

1.  If the price is too good to be true, be wary.

2.  Check the surface with a magnifier.  These fakes are poured, not stamped, and have visible pits on the surface under magnification.  Stamped coins may have scratches, but not relatively uniform pitting.

3.  Also, they contain little if any silver.  Check them with a magnet.  Silver is not magnetic.  These fake coins will be attracted to the magnet.