PATTERN Denga 1828 CПБ.
Bit 920 (R2), B 34 (RR), GM 43, Uzd 3208 (RR). Very rare. Authenticated and graded by PCGS SP 64 BN (# 38785348). Very choice brilliant uncirculated, Specimen strike.
The 1828 St. Petersburg mint patterns are distinctive for being struck in a collar and for their fine execution, according to Grand Duke Mikhailovich.