1953 Threepence

Hi

I wonder if anyone can help, I have a 1953 Proof set but have been told the threepence is not proof, is there any differences between the proof, uncirculated and circulated. I know the penny proof differs from the circulated/uncirculated so that was easy to check(and thats proof). I am being told the queens head should have a mirror finish? I have 2 or 3 sets and none of them has an obvious mirror finish.

Take a look at this:

https://www.rwbauctions.com/a00002-lot-3014-1953-queen-elizabeth-ii-proof-nickel-brass-threepence-graded-pf-69-ultra

Where did you see that the 3 pence in the proof set wasn't a proof coin?  According to SCWC (and also in Numista) there were 40,000 proof 3 pence coins minted.  That's the exact number SCWC reports for the 1953 proof sets.  If both of those are true then yours is a proof.