C.1920 Chinese 1 Yuan 'Fat Man Dollar' . Counterfeit

If it's that far underweight, I'd strongly suspect it isn't made of silver at all - or maybe just a very thin silver wash. The laws of phyics say that you can't have a fake that's significantly underweight, but otherwise identical in terms of size and thickness, and still have it reasonably high silver fineness - surely the density of this coin would have to be be significantly lower than normal.

I have a fake Chinese dollar that's even further underweight, at just under 19 grams. It's solid brass, with some kind of icky pseudo-silver wash applied to it that has now mostly rubbed off, and fake "tarnish" that seems to have been applied with a spray-paint gun:


Mine's a lot less authentic-looking than the OP's coin.

@mrw, this previous thread on real vs. fake Fat Man Dollars might be of some interest to you:

http://goccf.com/t/397629

If you determine specific gravity, I'd be interested to hear that number. Thx.

Already mentioned above about that numeral 5 that doesn't belong.
Apart from that, the smoking gun to me is not only the numeral 5, but it is on a 6 character legend.
The 6 character should just have a numeral 3.
Other years 8, 9 and 10 appear on the 7 character legend.

My go to SG method is much more simple when it comes to large coins where best accuracy is not critical.
To see the wrong composition from good coin silver it works well enough.
But as is usually the case, my suspended N-52 magnets would indicate if I should bother to make the SG test or not.