Jeanne Antoinette Poisson by François Hubert Drouais (location unknown to gogm)
From oceansbridge.com.
This Drouais portrait of Jeanne Antoinette Poisson is as close to a casual dress as I have seen in a French portrait.
Keywords: Drouais, Marquise de Pompadour, Marquise, French, mistress, Louis XV, curly coiffure, floral headdress, hat, bows, square decolletage, modesty piece, jacket bodice, buttons, elbow length tight sleeves, engageantes, lace, vee waistline, peplum, full skirt