On the left: the world-famous Mona Lisa painting that is hanging in the Louvre.

On the right: a younger-looking Mona Lisa that the Mona Lisa Foundation believes Leonardo Da Vinci painted earlier.

The foundation, which owns the “Isleworth Mona Lisa,” says that after 35 years of research, experts believe it predates the famed 16th-century masterpiece by about a decade. The group is presenting its findings to reporters Thursday in Geneva.

The Isleworth painting is slightly larger, was painted on canvas and has brighter colors than the Louvre masterpiece painted on wood.

Is it real?

Some art experts are highly sceptical and contend the work is more likely to be a later copy. Oxford University professor Martin Kemp said the Geneva portrait was probably a copy of the Paris version by an unknown painter who simply chose to make the subject younger, Reuters reported.

The “younger version” – which the Foundation says was probably painted around 1505 – is not new to the art world but has been locked away in a Swiss vault for many years.

It was discovered in 1913 by collector Hugh Blaker in a manor house in the west of England where it had hung for a century unnoticed.