A very nice piece with mint luster on both sides.
Obverse: crowned escutcheon with the coats of arms of the Crown and the Grand Duchy of Lithuania, above it in a half-arc the legend:
KROLESTWO POLSKIE, on the sides the date 18-31
Reverse: in an oak wreath an inscription 10/GROSZY/POLS-; under the wreath initials K-G- of Karol Gronau - manager of the Warsaw Mint in 1829-1834;