Watch List notes:

Potosi, Bolivia, cob 8 reales, 1650 O, with uncommon crown-alone (Mastalir K7) countermark on cross, very rare, Mastalir Plate. S-P35; KM-19b; Cal-1488. 19.09 grams. Broad flan (a bit smooth and thin from corrosion and silvery from cleaning), with well-detailed full shield and cross, nearly full king's name and ordinal, full 16 and top of 5 (modern) of date with dots between digits, 100% complete countermark in center of cross (one of just three known for this crown design on 8R, plus two more known on 4R). Pedigreed to the Roberto Mastalir Collection of Countermarked Potosi Cobs, Plate Coin (page 103 in Part A and page 305 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 tag and certificate. From: Capitana, sunk in 1654 off Chanduy, Ecuador
($400-600)