Napoleon era, c.1800-1815, a young beauty's likeness captured by a very adept miniature portraitist. At height of fashion for her time, the laciness of her hair is repeated at her fashionably low bodice, pulling attention to the artist's capture of her right nipple. Does it make this one a 'naughty' (sensual or outright sexual painting)? Of Isi it simply the fashion of her time. Both might be true. Without identification of the young woman, nothing of her history or if she might have been a young mistress to a Noble, we can only speculate. I find no artist's signature to aid in research, either. Just a beautiful young woman in blue, caught for a moment in time. Full measurements are noted on the photos.
Very good to excellent condition for age and type, it is over 200 years old at this point. Still perfectly kept beneath convex cover glass and brass mount, set as was typical, in the wood frame. It is likely that brass mount has a thin layer of gold (I did not text this one, not wanting to leave a scratch). In her era and class, it was often done - a thin plaque of gold - not plating and not foil, but slightly thicker, cast and affixed to the brass. We find it done often on snuff box and jewelry mounted miniatures of the era, and this has that look - no tarnish of age. I will mention it only, since I did not test this one.