Identifying old proofs is difficult

So I would not ask if I was sure, but I am not. This could just be a nice example of this coin. I have the 1947 one as well, which I know for sure is not a proof. going through my coins, I found the 1948 as seen in picture. It is cleaner now than it was when I found it, I tossed it in some warm soapy water for about a half hour, and then dabbed it clean, removed a ton of filth from it, it was black when I found it, so the cleaning example is profoundly different. Is this a proof, or just a well preserved coin from all the gunk that was on the surface. Please keep in mind, it is still tarnished, I did not clean tarnish off because I don't know how to do so without damaging the coin. Maybe you have a suggestion for that as well?

I think it is well preserved rather than a proof.

I would agree with Ben on this one.

UNC coins from the 40's is not uncommon