A nice piece with well-preserved details. Coin most likely removed from the setting.
On the obverse the initials of Pavel Stupitsyn.
Obverse: eagle of the Russian Empire, on the sides of its tail initials ПC, in the rim legend:
ПЯTЬ РУБЛЕЙ 1823;
Reverse: in a laurel and oak wreath the legend:
ЧИСТАГО/ЗОЛОТА/1 ЗОЛОТН=/39 ДОЛЕЙ-/С.П.Б.;
Gold, diameter 22.6 mm, weight 6.54 g.