in my collection is a "hybrid-spoon"!
prince
Assayer: Tverskoy D. I. 1837-1851
Maker: HE, Ehmke Johann Heinrich 1843-80 from Riga
It looks like there was an "export" from Riga-made spoons to St. Petersburg.....
Regards
Goldstein
source: PL, BS p. 315, Collection Goldstein