From Wikimedia; spots removed from background with Photoshop by gogm.
Margherita is probably portraying a saint in this Sustermans portrait from around 1628.
Keywords: 1628, Sustermans, Margherita de Medici, Medici family, Farnese family, Princess, Duchess, Italian, straight coiffure, scoop neckline, fichu, over-dress, square neckline, strap sleeves, under-dress, elbow length over-sleeves, long under-sleeves, cuffs, pendant, wrap