Portugal's first adhesive postage stamp — the "Selo D. Maria II" — was issued in 1853, making it among the earliest in Iberian philatelic history. This coin commemorates the 150th anniversary of that issue. The .500 fineness is characteristic of INCM's lower-tier commemorative silver output from this period, a cost-containment approach adopted across several early 2000s thematic series rather than any decision tied to the subject matter.
Portugal's first adhesive postage stamp — the "Selo D. Maria II" — was issued in 1853, making it among the earliest in Iberian philatelic history. This coin commemorates the 150th anniversary of that issue. The .500 fineness is characteristic of INCM's lower-tier commemorative silver output from this period, a cost-containment approach adopted across several early 2000s thematic series rather than any decision tied to the subject matter.