From pinterest.com/ccatany/spain-xvii-century-and-related-to-this-specific-fa/. Also posted to her Subalbum here.
Most Spanish brooches shown are circular, but this one is rectangular, probably centered on a Madonna portrait.
Keywords: 1665, Barnuevo, Infanta Margarita, Margarita Teresa de Austria, Infanta de España y Emperatriz consorte del Sacro Imperio Romano Germánico, Kaiserin des Heiligen Römischen Reiches, Königin in Germanien, Princess, Empress, Habsburg family, Spanish, long straight coiffure, jeweled ribbon headdress, straight neckline, lace bertha, brooch, puffed virago sleeves, ribboned arm bands