20 Francs Wiener pattern

In 1873, Switzerland was under considerable pressure to abandon its bimetallic Franc system and align with the Latin Monetary Union's gold standard. The Wiener pattern — named for Heinrich Wiener, the Prussian-born medalist commissioned to produce trial pieces — was struck as part of that deliberation, exploring a 20-franc gold denomination that would have placed Swiss coinage on direct parity with French and Belgian issues of identical weight and fineness. The pattern was never adopted; Switzerland would not standardize a circulating gold 20-franc until the Vreneli series began in 1897.

Wiener produced several distinct trial types during this period, making attribution among the Pr2, HMZ, and KM pattern references occasionally inconsistent across auction records.