I have a 2006 silver proof set. A couple of days going while looking over them to catalog them a noticed that the cent in the 2006 silver proof set had 4 bumps between the D and the S in United States. I guess what my first question is, is this an error and how rare is it? Thanks for your help.
well, not rare, and technically an error. Bubbles in the plating. No one, that I know of collects these. Considered more like damage.
