From Wikimedia; removed spots in background with Photoshop and doubled size. Also posted to the Late Farthingale Era - 1590 to 1620 here.
Caterina stays loyal to the Spanish saya in this 1621 portrait.
Keywords: Caterina di Ferdinando de' Medici, Caterina de’ Medici, Catherine de' Medici, duchessa di Mantova e di Monferrato, governatore di Siena, Medici family, Gonzaga family, Duchess, Italian, curly coiffure, circlet, earrings, jeweled fitted tabbed basque bodice, lace neckline ruff, high neckline, tabbed jeweled hanging sleeves, long false sleeves, lace back-flared cuffs, brooch, draped jeweled bodice ornament, jeweled A-line skirt, saya