Watch List notes:

Potosi, Bolivia, cob 8 reales, 1650/49 O, with uncommon crown-alone (Mastalir K1a) countermark on cross, very rare, Mastalir Plate. S-P35; KM-unl (19b for type); Cal-unl (Type 327). 21.64 grams. Broad flan with much flatness but clear P-O to left and parts of all four digits of date and overdate, toned and only minimally corroded (probably struck in low weight), its best feature a 100% complete and fully detailed countermark, with large natural edge-crack. Pedigreed to the Roberto Mastalir Collection of Countermarked Potosi Cobs, Plate Coin (page 72 in Part A and page 236 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. From: Capitana, sunk in 1654 off Chanduy, Ecuador
($400-600)