Thank you very much for all the answers. As I mentioned, I kept the 1903 piece.
@EarlyTurban
To be honest I am quiet shocked about the grading skills of american collectors. I collect german gold coins and for my little trip to US gold I try to educate myself with pictures of gradet coins and ''unboxing'' videos. I have the impression that lots of us collectors are not able to estimate the condition of raw coins. Thats the result of giving the homework to someone else

. In my opinion you do not necessairy need guides. You only need an eye for details and lots of pictures to compare.