20 Mil Réis Thesouro Nacional, 1st print

Brazil's National Treasury turned to Perkins, Bacon & Petch at a moment when the London firm's intaglio security printing — developed largely through Jacob Perkins's steel engraving innovations — was considered the hardest to counterfeit in the world. The same technology had already been applied to early U.S. banknotes and British penny black stamps. For a young imperial government struggling with monetary credibility, the choice was deliberate.

This is the first print of the series, distinguishable from later emissions by subtle plate details that specialists have catalogued but which were invisible to ordinary users at the time — which was entirely the point.