Watch List notes:

Potosi, Bolivia, cob 1 real, (1649) O/sR, unique, ex-Mastalir (Plate). S-P35; KM-unl; Cal-unl. 3.34 grams. Bold full P-O with clear evidence of sR under-assayer (first and only example known in any denomination except the 8R--see lot 205 for explanation), also with full cross and most of shield, About Fine details with cleaned surfaces punctuated by spots of black oxidation, a unique and important coin for the specialist. Pedigreed to the Robert Mastalir Collection and plated on pages 47 and 244 of Part A of his book The Great Transition at the Potosi Mint, 1649-1652: The 1649-1652 Crowned Shield Coinage and the Countermarks of 1652 (2021).

Estimate: $250 - $375