⅙ Thaler - Frederick William III

KM#Pn15 designates this as a pattern issue — Prussia was in the midst of rationalizing its coinage system in the years following the Napoleonic wars, and the 1817 date places this squarely in the experimental phase before Frederick William III settled on the architecture of the 1821 currency reform. The ⅙ Thaler denomination itself had a contested place in that process; several competing fractional schemes were proposed and struck in pattern form before the Silbergroschen system was adopted.

The .750 fineness is worth noting as a policy choice, not a technical one — debates within the Prussian mint administration over silver content were unresolved at the time of striking.