São Tomé de 12 Xerafins - João Prince Goa mint

The xerafim was a unit of account deeply embedded in the Indo-Portuguese monetary system, and by the early nineteenth century its gold denominations were caught between two pressures: the disruption of Portuguese imperial finance following Napoleon's invasion of the peninsula in 1807, and the chronic shortage of bullion reaching Goa as the Estado da India contracted around its last viable coastal enclaves. João, ruling as Prince Regent from Brazil after the court's flight from Lisbon, nominally authorized this coinage from across the Atlantic.

Goa's mint was notoriously inconsistent in planchet preparation during this period, and weight variation within the type is common.