Nicely preserved details.
Opening.
Obverse: head to the right, in the rim legend:
STANISLAUS AUGUSTUS D.G.REX POL.M.D.LIT.;
Reverse: crowned five-field escutcheon with the coats of arms of the Crown of the Kingdom of Poland, the Grand Duchy of Lithuania and the Poniatowskis, encircled by the Order of the White Eagle on a ribbon and an oak-palm wreath, in the rim legend:
20 7/8 EXMARCA PUR:-COLONIENS:1788./E.B:;