Thank you for posting this. It helps to see real world examples of what is coming from China. The design and processing leave a lot to be desired (look at the two stars adjacent to the "E" of EPU), but I'll bet the weight and specific gravity aren't too far off.
Specific gravity of 19th Century U.S. 90% silver coins should be within a standard deviation of 10.25 (roughly between 10.16 and 10.34). This can be emulated with Ag plating over a core of approximately 87% Pb and 13% Sn. I'll bet that's pretty close to what lies in the core of this coin.
There are three nondestructive tests that can be performed:
1. The "ping" test. Balance this coin on one finger and gently "ping" it with a known genuine 90% silver coin. Then do the same by pinging one known genuine 90% silver coin with another known genuine 90% silver coin. The resonant frequency will be sharply different.
2. Use an eddy current brake slide. Silver, copper, and aluminum react the same, by generating an electrical field ahead of the sliding coin, slowing the coin as it descends the slide. (This is Lenz's Law, used for electromagnetic brakes on trains, for example.)
3. Specific gravity test.
Edited by fortcollins
11/24/2018 6:30 pm