Whether Leonardo's or not, it is not uninteresting to read how the picture affected Shelley when he saw it here in 1819:-- ...

Its Horror and its Beauty are divine.
Upon its lips and eyelids seem to lie Loveliness like a shadow, from which shine, Fiery and lurid, struggling underneath, The agonies of anguish and of death.
The little room leading from this one should be neglected by no one interested in Medicean history, for most of the family is here, in miniature, by Bronzino's hand.

Here also are miniatures by other great painters, such as Pourbus, Guido Reni, Bassano, Clouet, Holbein.

Look particularly at No.

3382, a woman with brown hair, in purple--a most fascinating little picture.