^Lot 221 Potosi, Bolivia, cob 4 reales, 1651 O, with uncommon crown-alone (Mastalir K5) countermark on cross,

Potosi, Bolivia, cob 4 reales, 1651 O, with uncommon crown-alone (Mastalir K5) countermark on cross, very rare, ex-Ponterio, Mastalir Plate. S-P35; KM-17b; Cal-1107. 9.48 grams. Thin (from corrosion) but round, with well-centered strike, the date exceptionally bold and full, also bold P-O to left and clear 4-O to right of full shield, nicely toned, with deep countermark (also seen on Atocha [1622] silverware) in very center of cross, apparently the only example known in this denomination. Pedigreed to the Roberto Mastalir Collection of Countermarked Potosi Cobs, Plate Coin (page 128 in Part A and page 292 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), and also pedigreed to the "La Capitana" auction by Ponterio (April 1999), with original lot-tag 37 and generic certificate. Recovered from: Capitana, sunk in 1654 off Chanduy, Ecuador