The Swiss-based Mona Lisa Foundation art foundation revealed on Thursday what it says to be Leonardo da Vinci's original "Mona Lisa." In a press conference in Geneva, the foundation backed its claim with evidence from a U.S. research physicist, a forensic imaging specialist and a top Italian expert on the artist.
Representatives from the foundation told members of the press that the woman in the "original Mona Lisa" is the same woman in the painting, but 10 years younger, and is Da Vinci's original work.
Reuters reports that the "Isleworth" is larger than the "Mona Lisa" and shows a woman in an identical pose, with the same smile and same geometric proportions.
"The facts are overwhelming and clearly prove the authenticity of the masterpiece," said Swiss lawyer Markus Frey, president of the private Mona Lisa Foundation, Reuters reports.
The painting is being called the "Isleworth Mona Lisa, and the foundation is says, in a 300-page publication, it was painted between 1503 and 1505 in Florence, but was never actually completed.
The foundation has come under criticism for these controversial claims.
British Leonardo authority Martin Kemp doesn't believe the painting is by Da Vinci, telling a London newspaper "so much is wrong" with the painting and that Da Vinci preferred paint on wood, and not canvas.
"So much is wrong. The dress, the hair and background landscape. This one is also painted on canvas, which Leonardo rarely did," Martin Kemp, emeritus professor of the history of art at Oxford, told The Sunday Times.
Reuters says the "younger" version first surfaced in 1913 when British art connoisseur and painter Hugh Blaker found it in a manor house in western England, recording that it had been hanging there for about 150 years.
For the next 20 years, it hung in his home in the London suburb of Isleworth, so gaining its name.
"She might look younger but this is probably because the copyist, and I believe it is a copy done a few years after the Mona Lisa, just painted it that way," Kemp added.
The painting has been owned by a private consortium since 2008.