Watch List notes:

Potosi, Bolivia, cob 4 reales, 16(1)9T, rare, Grade 1, with tag only (certificate missing). S-P21; KM-9. 12.99 grams. Bold but off-center full shield and cross, bold P-dot-T, weak but certain date (surprisingly somewhat rare), no corrosion, toned in crevices. With Fisher tag #8884. Santa Margarita, sunk in 1622 west of Key West, Florida

Estimate: $350-500