Also I've seen 1950/51 fakes, and bust gives it away with far too many incuse hair grooves, hyper-accentuated details, that just look off. But some of these are very good, all the same.
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A comment from predecimal forum, where I shared a link to this, by the man who runs this informative blog
https://headsntails14.wordpress.com/That reverse is scarily good - I had to count the teeth to make sure but the fake has 180 teeth whereas the genuine article has 187.