Russia, Empire. Nicholas I AR Rouble. St. Petersburg mint, 1840/39. ✸ ЧИСТАГО СЕРЕБРА 4 ЗОЛОТНИКА 21 ДОЛЯ, crowned double-headed eagle facing with wings spread, wearing shield on breast depicting St. George slaying the dragon, with shields arranged across wings, and holding sceptre and orb; crown above, H-Г across lower fields / Denomination over date, C.П.Б. below; crown above and wreath around. Edge inscription: • СЕР • 83 1/3 ПРОБЫ 4 ЗОЛ • 82 14/25 ДОЛИ. Bitkin - (overdate not listed), cf. 183.
PCGS graded MS 63 (#28502237). Extremely Rare; Bitkin makes no mention of this apparent overdate.
From the GK Collection (France) of Russian Coins.
The reverse die for the present rouble was used for two consecutive years, with the date being re-cut to read 1840 from the original 1839, as can be seen clearly here.