Her Wikipedia article is here. She was a direct descendant of Hortense Mancini and she bore her first husband, Prince Honoré IV of Monaco, two sons who both had a chance to rule Monaco. She also bore two illegitimate daughters. Their marriage ended in divorce in 1798. She was a Duchess suo jure.
This is probably excerpted from the next image that lists the artist and location.
From the lost gallery's photostream on flickr.
Louise Hippolyte poses in a late 1770s coiffure and satin dress trimmed with ribbons and lace, nicely dressed for guitar practice. One of the the tent-like panels of a zone bodice can be seen between her hand and the guitar. For all of the spectacle, she wears no visible jewelry.
Keywords: Vestier, Louise Félicité Victoire d'Aumont, duchesse de Mazarin, Louise d'Aumont, duchesse d'Aumont, duchesse Mazarin et de La Meilleraye, princesse de Monaco, d’Aumont family, Grimaldi family, Duchess, Princess, French, high straight big curl coiffure, ribbon headdress, chemise, lace modesty piece, lace elbow length bottom flared cuffs, zone bodice, ruching, elbow length close sleeves, ruffled forward-back flared engageantes, bows, full skirt