Watch List notes:

Potosi, Bolivia, cob 4 reales, 1651 E, with crowned F or T countermark on shield, rare, Mastalir Plate. S-P36; KM-17b; Cal-1108. 12.17 grams. Very broad flan with only light corrosion but large edge-crack, toned in crevices, some peripheral flatness but the cross and shield full, with clear 4-E to left, full king's ordinal IIII, bottom half of 65 and full final 1 of date, and just the top (crown) of the countermark on the shield. As Mastalir points out, 1651 E is quite rare in this denomination--just 13 known--and this is a unique subtype. Pedigreed to the Roberto Mastalir Collection of Countermarked Potosi Cobs, Plate Coin (page 147 in Part A) 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 copy of Herman Moro certificate. From: Capitana, sunk in 1654 off Chanduy, Ecuador
($350-500)