Since he's posting from Hong Kong it's logical to be posted in the Foreign Coin section. As far as authenticating the coin - I'll go out on a short limb and say the coin is a counterfeit. The lettering and devices all have a soft, rounded look where they should be sharp and crisp. That, coupled with its Hong Kong location lead to the conclusion I made.
Compare the OP's vs a known authentic one. Uneveness of the ball-and-bar "dentils". Rounded lettering. Graininess in the surface of the wall. Weakness in details of Liberty's robe. The whole coin, especially the reverse, looks like a casting. I could be wrong about this, but my opinion is that it's not authentic. It may have made a round trip from China to the US and back to Hong Knog.
This is not my area, but I have no idea what you are seeing, David. The 1920 you have pictured looks like it is cast compared to the 1925. His pics are not big enough for me to see much about the denticals, but there is nothing that strikes me as odd.
