Mona Lisa replicas and reinterpretations
After restoration, the Prado's "Mona Lisa" revealed details covered by previous restorations and layers of varnish.
Furnishings and fabrics were enhanced, as well as landscape and facial features.
It is anticipated that such revelations may offer further insight into Leonardo's original.
Experts at the Louvre reportedly supported the Prado museum's findings.
The Prado replica was subsequently transported to the Louvre in 2012 to be displayed next to "Mona Lisa" as part of a temporary exhibition.
Two nude paintings bearing similarities to Leonardo da Vinci's original were part of a 2009 exhibition of artwork inspired by "Mona Lisa".
Displayed at the Museo Ideale in Leonardo's hometown of Vinci, near Florence, some believe one of the paintings – dating from Leonardo's time – to be the work of Leonardo himself, and it has at times been credited to him.
Other experts theorize the painting, one of at least six known to exist, may be just another copy painted by "followers" of Leonardo.
Scholarly dispute persists as to artist, subject and origin.
The nude in question, discovered behind a wall in a private library, reportedly belonged to an uncle of Napoleon Bonaparte, who owned another of Leonardo's paintings.
Facial features bear only vague resemblance, but landscape, compositional and technical details correspond to those of the "Mona Lisa" known worldwide today.
The Theft of the Mona Lisa
In 1911, Vincenzo Peruggia is a poverty-stricken Italian glazier who falls in love with Mathilde, a French hotel maid. Struck by the girl's resemblance to Leonardo da Vinci's "Mona Lisa", Vicenzo manages to steal the painting from the Louvre in hopes of impressing his sweetheart. But when the girl proves to be a fickle sort, the crestfallen hero confesses his crime and is carted off to jail. Unwilling to admit that he'd been led astray by a woman, Vicenzo claims that he stole the "Mona Lisa" to restore it to his native Italy, and as a result is hailed as a national hero!