1680 (estimated) Anna Maria Luisa de Medici, Electress Palatine, Grand Duchess of Tuscany by ? (location unknown to gogm)
Anna Maria Luisa de Medici wears a gorgeous lavishly jeweled bodice and hurluberlu coiffure in this portrait. I am unable to locate the date, artist, or museum for this Internet favorite.
I estimate she's in her teens or twenties, putting this in the 1680s.