^Lot 1643 Potosi, Bolivia, cob 8 reales, 1650 O, with pentagonal crowned-1652 (Mastalir P52) countermark on cr

Potosi, Bolivia, cob 8 reales, 1650 O, with pentagonal crowned-1652 (Mastalir P52) countermark on cross, rare, Mastalir plate. S-P35; KM-19b; Cal-1488. 12.43 grams. Very thin from corrosion but with most of the pentagonal countermark (all but the date at the bottom) and 0 of date at top visible on nicely toned cross side, silvery full shield and clear assayer despite corrosion loss, small edge-split. Pedigreed to the Roberto Mastalir Collection of Countermarked Potosi Cobs, Plate Coin (page 386 in Part B) in his book The Great Transition at the Potosi Mint, 1649-1653, The 1649-1652 Crowned Shield Coinage and the Countermarks of 1652 (2021), with original Herman Moro certificate. Recovered from: Capitana, sunk in 1654 off Chanduy, Ecuador