The original relief art was done by Bertrand Andrieu and his signature can be faintly seen underneath Napoleon. 

Great gift item for the Napoleon collector. 

I do not know when this was cast but found another one in which it is described as porcelain. This could be made of porcelain bisque as well. 

Overall measurement is 3.5" in frame. The medallion measures approx 2 5/16".

See photos.