According to the Dannreuther-Bass book, there are slightly more than a dozen known 1831 Small D Capped Head Left Half Eagles in existence today. The Small D variety is believed by many experts to be three or four times more rare than its Large D counterpart. The Encyclopedia of U.S. Gold Coins: 1795-1933 by Jeff Garrett and Ron Guth speaks to the possible existence of the Proof 1831 half eagle. They say "despite as many as three citations for Proof 1831 half eagles, the authors have yet to identify a single example. The coin in the Smithsonian is a gem MS-65, but definitely not a Proof. No examples have appears at auction for more than a century, and not a single coin has ever made its way to the open market." They go on to argue that the proof 1831 could still exist, but that it is tightly held and rarely seen if so.

The example to the left was sold by Stack's Bowers Galleries in the D. Brent Pogue Part IV Auction, where it realized $646,250.