Rather than being a prototype, that dime is the result of a Proof die, produced at the Philadelphia Mint, that lacked the San Francisco Assay Office’s S Mint mark. The auctioneer looked to the 1975-S Roosevelt, No S dime that sold for $456,000 at a 2019 Heritage auction for guidance, as it is one of just two known examples of that classic 1970s rarity. Heritage advised potential bidders, “We would not be surprised if the new owner has the opportunity to place this coin on loan to any of these worthy institutions, among many others, and hope that he or she would accept such an invitation.”
The Smithsonian’s National Numismatic Collection lacks a representative, as do the major numismatic museum collections.
