I am not positive, but I think this is a portrait miniature 'aprés' or after a painting of Napoleon's 2nd wife, Empress Marie-Louis of Austria, the mother of his only child, ill-fated Napoleon II, who spent a very lonely life after Napoleon was deposed and his mother 'dumped' him with her mother. Poor NII died of consumption at age 21, Schonbrunn Palace, Vienna. If I'm right, this is a quite favorable view of her, and would have been made for the Grand Tour tourist market, mid-1800s. A superb hand painted portrait miniature in grisaille, monochromatic, and set into a dore bronze vanity mirror, likely part of a set originally with other members of Napoleon's family. Kiln-fired enamel mat, and elegant mousing on this fine old mirror. It would date c.1860-1900 at latest. The miniature is hand painted, still backed with the old original vellum backing as you can see, with an identifying sticker.
Very good to excellent condition for age and type, the mirror is beveled and in very nice form, and the dore bronze casing/frame is just stunning. Kiln-fired convex oval mat shows a couple of imperfections in the surface enamel, visible on photos. The painting is stunning, and rare in grisaille. Together, a magnificent vanity item.