Is this a lost Da Vinci artwork?

7AM
Is this a lost Da Vinci artwork?
Art experts are examining a sketch as the possible basis for Leonardo da Vinci's Mona Lisa.
The charcoal drawing, known as the Monna Vanna, has been kept in a collection for more than 150 years.
It was thought to have been drawn by a student of Leonardo Da Vinci.
But now clues suggest it may be the work of the master himself.