A very nice piece, with perfectly preserved details.
Micro scratches in the background.
Obverse: head of the king to the right, in the rim the legend:
STANISLAUS AUG.D.G.REX POL.M.DL.;
Reverse: crowned five-field straight shield of arms with the coats of arms of the Crown, the Grand Duchy of Lithuania and the Ciołek coat of arms of the Poniatowskis, girded by a ribbon with the Order of the White Eagle, with rectangular labrums with blue tint (most likely symbolizing the end of the order ribbon, which was made entirely in that color); below it, separated by the Order initials E.-B. and the denomination 8.-GR., surrounded by the legend:
41 3/4 EX MARCH-PURA COLON:/1787;
