Her Wikipedia article with this image (doubled in size by gogm) is here.
Holy Roman Empress Eleonora wears a Habsburg dress imported from their Spanish holdings, a saya with a vestigial ruff, in this Luyckx portrait.
Keywords: Luycx, Eleanor Gonzaga (1630-1686), Gonzaga family, Habsburg family, Princess, Empress, Austrian, hurluberlu coiffure, jeweled headdress, straight neckline, ruff, modesty piece, bertha, lace, long puffed false sleeves, back flared engageantes, hanging sleeves, basque waistline, over-skirt, necklace, brooch, jeweled bodice ornament, bracelets, fan