Andrea del Verrocchio:

Head of a Young Woman
(Black Chalk with a little bodycolour - Guise Bequest1765)

The outlines of the depicted face are pricked for transfer, but the surface of the drawing is so finely worked and the hatching so precisely placed, that it may have been kept as a sort of "master cartoon" for future use by assistants rather than a cartoon (a one-to-one model drawing) that could be destroyed after its use.

Verrocchio was a painter, sculptor and draughtsman who ran one of the largest and busiest workshops in Florence, in which many important artists were trained; by far the most famous among them was Leonardo da Vinci.