For your consideration: Military Medal from Imperial Russia issued in. Commemoration of Imperial School established in 1820. Very nice medal that appears not to be cleaned before. And has just couple of nicks and marks on obverse. Medal is heavy and I do believe it's made of silver.
But can not exclude that it's a silver plated Brass which I can't verify. Diameter: 56 mm (2.19). Metal: Silver or silver plated brass. All expressed opinions are my own and may be subjective in nature. Therefore, please use provided photos to form your own opinion.
If any questions or additional information are needed please send me a message. And I'll reply with an answer as soon as possible.