As I've explained, there are basically 2 types of portrait miniatures: 1. a living person who sat for their portrait in real life, and 2. those done "après" famous works of art in the museums, fueled by the souvenir hungry Grand Tour travelers. This is a Grand Tour portrait miniature, after the work Portrait of Juliette Récamier by François Gérard (1805, detail), which is on display in Musée Carnivalet, Paris. The miniature painting dates sometime after that, likely (from the frame) mid-1800. It is a larger sized portrait miniature and still is backed by vellum.
Very good condition for age and type. The old pressed-embossed oval frame joins at the top and that final is a screw which holds the posts of each side of the frame tightly together, with cover glass, painting and vellum backing within. The wafer has 2 long tight hairlines, marked on our photos for your review. Stable beneath the original cover glass, it is from the natural shrinkage of the panel, nothing more. Visible at angles, but does not traverse the figure except at one shoulder. Here we have a painting done by an artist who has signed his or her work, and likely painted it seated before it in the Louvre back then. I've included a detail from Gérard's original for comparison, but of course it is not included. Just to show the painting this artist was looking at as he or she copied the work. Measurements are noted on our photos.