Both images from Wikimedia; both image sizes doubled.
Infanta Maria Isabel wears a band of jewel stars as a ferroniere. Her neckline and sleeves are edged with matching double bands of tulle-like material.
Keywords: 1820, van Hanselaere, Maria Isabella of the Two Sicilies, Borbón family, Borbone family, Princess, Queen, hurluberlu coiffure, tiara, feather headdress, veil, lace, ferroniere, square neckline, modesty piece, quarter length puffed sleeves, cuffs, jeweled waist band, Empire waistline, close skirt, order sash, order bows, necklace, earrings, gloves, shoes, hosiery, robes, regalia