A charcoal portrait of a nude woman is now thought to be a study for the Mona Lisa.
The work was previously attributed to Leonardo da Vinci's studio, but experts have lately determined that the Renaissance master likely created the charcoal sketch, based on its size, age, stylistic elements, and small holes where it appears the work was traced.
Louvre curators believe the sketch is "at least in part" by Leonardo. A right-handed assistant possibly worked on part of the cross-hatching.
“It has a quality in the way the face and hands are rendered that is truly remarkable," curator Mathieu Deldicque told the AFP. "It is not a pale copy."
The charcoal has resided since 1862 in the collection of Renaissance art at the Conde Museum at the Palace of Chantilly, north of the French capital.