"Portrait of a lady, seated, three-quarter-length, in a silk grey dress and blue shawl, in a landscape", Antoine Pesne
Portrait of a woman, presumably wilhelmine of prussia, margravine of brandenburg-bayreuth (1709-1758), sister of frederick ii of prussia (1712-1786)
identification proposed by user ecummenic (talk) based on the comparison with a portrait of that princess (see the first image below). Date: 18th century. Dimensions: height: 18.7 cm (7.3 in); width: 15.2 cm (5.9 in). Medium: oil on canvas. Collection: Unidentified location. Attributed to Pesne - Portrait of a lady in a silk grey dress and blue shawl