This is the
daughter of Queen Sophia Dorothea and King Friedrich Wilhelm of Prussia. Her
Wikipedia article is here.
This 1734 portrait of princess Friederike Luise of Prussia is a good example of 1730s German dress.
Keywords: 1734, Friederike Luise of Prussia, Hohenzollern family, Princess, Prussian, straight coiffure, hair jewelry, square neckline, modesty piece, close elbow length sleeves, engageantes, lace, stomacher, vee waistline, full skirt