By the time this portrait was painted, probably in the late 1820s, Maria Stella was Baroness Ungern-Sternberg as she had been since 1810. Her article in thepeerage is here.
From the Bonham's Web site; image made lighter while contrast was increased to bring out some detail. The center strap of her pleated bodice is barely visible.
Baroness Maria Stella wears a black evening dress with just a modesty piece, brooch, and modesty piece to provide color relief.
Keywords: Beechey, Lady Maria Stella Newborough, Lady Newborough, Maria Stella Chiappini, Chiappini family, Wynn family, Ungern-Sternberg family, Baroness, turban, modesty piece, scoop neckline, pleated bodice, vee neckline, quarter length puffed sleeves, belt, jeweled buckle, natural waistline, full skirt, brooch