Rare example made by imperial russian porcelain factory.
Fine quality porcelain plate from "tsarskoe selo" palace service.  
Circa 19th century, alexander ii regency (1855 - 1881). 
Marked on the back with green color factory mark / alexander ii royal monogram. 
Set of similar plates was sold at christie's, london on november 27, 2017 for 23,750 british pounds (approximately $31,350 by nov, 2017 exchange rate). Please see last picture for reference.
   Size:
About 9 13/16 in. (25 cm) diameter. 
   Condition: 
One shallow chip on the back side, unnoticeable from the front. 
Expected wear to gold. 
No previous restoration.