From Wikimedia; enlarged by half. Also posted to the Reign of Louis XV - 175 to 1774 Album here.
Details of the sleeves, especially the cuffs or engageantes, are hidden. The wide skirt and coiffure are 1700s.
Keywords: Eleonore von Schwarzenberg, Eleonore Elisabeth Amalia Magdalena, Prinzessin Eleonore Elisabeth Amalia Magdalena von Lobkowitz, Fürstin zu Schwarzenberg, Eleonora Amálie ze Schwarzenberka, Lobkowicz family, Schwarzenberg family, Princess, Austrian, long curly coiffure, jeweled headdress, lace-edged chemise, modesty piece, off shoulder scoop neckline, lace cuffs, fitted bodice, Sévigné bodice ornament, full sleeves, girdle, vee waistline, full skirt, robes