Just wondering what if any, rarities are something likely to get through on a U.S. Mint proof coin. I am thinking that discoloration is about the only thing that is possible, but then again I don't really know. Can someone shed a little light on this issue for me.
its possible, and yes, there are coin proofs out there that contain errors. but because or the more stringent process and qualirty checks, they are less seldom seen then circulation errors.
I have a cent I removed from a proof set that has a thin wire attached to the edge. It looks like a portion of the rim may have been clipped on the second stamping of the coin, and it was retained.
I also saw a very impressive depression on a proof Eisenhower dollar, likely caused by foreign material being on the die. This was on eBay about 1-2 months ago. It was still enclosed in the original proof set case.
On proofs I've seen clipped planchets die cracks Doubled dies Mis-aligned dies Rotated dies Strike throughs Wrong design (such as the 1998 close AM) and the out of order edge inscription on the Jefferson dollars. There are probably more types.
The only error obvious to me is that you've posted a copyrighted picture without a permission citation. Less obvious due to a bad photo is that it appears to be slightly oblong - perhaps struck out of collar.
That is a variety, not an error. An error occurs during the coining process, usually during striking. Errors can be off center, broadstrikes, clipped planchets, etc. A variety occurs during either the design process (e.g., wide AM) or during the die-making process (e.g., RPM or Doubled Die).
I'd say his posting of the picture would fall under "fair use". And Hobo is right about the wide and close AM cents, those would be varieties not errors. My error.