From magika42000's photostream on flickr; spots throughout image and the lower part of the right side fixed with Photoshop by gogm.
Isotta's partlet matches the under-partlet in the previous image. She is wearing it over a chemise decorated with red embroidery something like English blackwork. The puffed cloth ornaments protruding through her sleeve rolls match the partlet.
Keywords: Moroni, Isotta Brembati, Isotta Bermbatti, Isotta Brembati Grumelli, Brembati family, Grumelli family, Italian, straight coiffure, jeweled ribbon headdress, partlet, high neckline, neckline ruff, chemise, off shoulder bateau neckline, over-bodice, rolled sleeves, puffed cloth ornaments, bows, necklace