Hi guys, I have this 1968 S Lincoln Proof Penny and would like to know what is going on with the S mint mark. Are these die chips in between the curves of the "S" which make the "S" look filled in? Is this common on a 1968 S Lincoln Proof Penny?
You're correct. Die Chips (Internal Die Break). It's not an RPM. Not sure if it's common on proofs, but I don't believe it adds anything to the value.