12800 Réis - João V 1st Type of Shield, Rio de Janeiro Mint

João V's gold coinage of the late 1720s was funded almost entirely by the Minas Gerais gold rush — the largest gold strike the Americas had yet produced — which by the 1720s was delivering bullion to Rio de Janeiro's mint faster than the colonial administration could reliably process it. The 12800 réis, equivalent to a full gold dobra, was the highest denomination in circulation and moved primarily between merchants, Crown tax collectors, and transatlantic trade settlements rather than in any ordinary commerce.

The "1st Type of Shield" distinction matters: a redesign of the escutcheon followed within a few years, making this a short emission window of roughly four years before the type was superseded.