Her son, the 15th Duke of Medina Sidonia's, Wikipedia article includes this, "Don José María Álvarez de Toledo y Gonzaga, 15th Duke of Medina Sidonia, 11th Marquis of Villafranca del Bierzo, Grandee of Spain, jure uxoris Duke of Alba de Tormes, Grandee of Spain (16 July 1756 – 9 June 1796) was a patron of the artist Francisco Goya... ...He, originally Marquess of Villafranca, married his kinswoman Doña María del Pilar Teresa Cayetana de Silva y Álvarez de Toledo, 13th Duchess of Alba who was the legendary 'Duchess of Alba' in Goya's paintings, thus becoming de jure uxoris Duke of Alba..."
Alta resolución images from the Prado have great detail that, in this case, included numerous speckles and flaws that I removed with Photoshop. That image did not upload properly so I copied it with screen shots and reassembled it. The reassembled image is posted.