A nice example of this issue with well-preserved details.
Obverse: eagle of the Russian Empire, on the sides of the eagle's tail the initials ПС, in the rim the legend:
МОНЕТА РУБЛЬ *1819*;
Reverse: in laurel and oak wreath crowned inscription: ЧИСТАГО/СЕРЕБРА/4 ЗОЛОТН-/21 ДОЛЯ./С.П.Б..;
Edge: СЕР . 83 1/3 ПРОБЫ 4 ЗОЛ . 82 14/25 ДОЛИ;