Her Wikipedia article is here.
From WikiPaintings.
This is another Boldini portrait of a woman in a seductive pose, this rime with a bared shoulder, feathers, and a full coiffure with a tiara.
Keywords: 1911, Boldini, Princess Bibesco, Princess, curly coiffure, tiara, close skirt, shoes, floral bodice ornament, boa, feathers, fan