See Also:  Unused Cardbacks

A Proof Card is a prototype of the cardback, used to approve or make changes to the final product before printing.  These are different from Unused Cardbacks in a few ways.

These are general guidelines to identify a proof card:
1) Proofs are often signed or marked on.  Granted this isn’t foolproof because anyone can mark on an unused cardback after the fact, but it’s still a good indicator.
2) The punch tab is usually a different shape than the production cardbacks.
3) The coloring is usually different, a bit lighter, and not as cleaned up as the production cardbacks.
When all else fails when trying to identify, ask an expert in the forums if you’re unsure.

(Collection of: Ken Rohlf)