The Newcomb-18 variety is a Proof-only variety and shares a reverse die with several other Proof cents. When Walter Breen wrote his study of Proof coins, he suggested that "there may be more than a dozen around in all," and enumerated seven or eight examples. The more recent and actively updated data kept by Denis Loring suggests that the number of N-18 specimens may be just a little higher. Denis Loring also considers some strikings of Newcomb-30 to be proof strikes, but thus far that information has been unfounded.

The example to the left was sold by Stack's Bowers Galleries in the July 2015 Baltimore Auction, where it realized $14,100.