A nicely preserved piece.
The year is known for the most numerous ducat issue, but this should not be equated with rarity - the number of issues is followed by the number of varieties, some of which are exceptional specimens. The present piece belongs to a variety with legends ending in FRAT and WOL.
Obverse: three half figures of princes in armor, below them an ornament, in the rim a legend:
D:G-GEORGIUS-LUDOVIC-& CHRISTIA-FRAT-(apple).
Reverse: four-field escutcheon in cartouche, surmounted by crest jewels, in outer rim legend separated by rosette and mint mark (heart pierced with hooks - Christian Pfahler):
DUCES-SILESIÆ LI-GN-BREG-& WOL-1659
Diameter 22 mm, weight 3.42 g.