Called "La Belle Corisande," she was one of Henri IV's glee girls. Her German Wikipedia article is here.
Diane d'Andouins (?) wears a conical farthingale with just about all of the trimmings, including an over-skirt that casts a shadow on the under-skirt and otherwise exactly matches it.
Keywords: 1565, Anguissola, Countess, French, Mistress, Henri IV, curly coiffure, jeweled cap, high enclosing neckline, ruff, tabbed sleeves, hanging sleeves, long tapered false sleeves, cuffs, girdle, tabbed bodice, vee waistline, farthingale, over-skirt, carcanet necklace, earrings, aglets, handkerchief