It is a painting lost for so long that many art experts had begun to believe Leonardo Da Vinci had never actually found the time to finish it.
However, the art world is used to discovering "new" masterpieces that are often centuries old. In September, a Vincent Van Gogh landscape was discovered in a Norwegian attic.
Now, an apparent Da Vinci has been found in a Swiss bank vault.
The portrait of an Italian Renaissance noblewoman called Isabella d'Este was discovered among a private collection of 400 paintings in the bank vault of an unnamed Italian family.
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It is believed to be the oil version of a pencil sketch of the same woman that currently hangs in the Louvre Museum in Paris.
Da Vinci's sketch was completed in either 1499 and 1500 when he stayed in Mantua in the northern Lombardy region.
D'Este sent letters to DaVinci asking him for a new version of the sketch in oils, yet the letters went unreturned, with many Da Vinci experts believing that he had simply moved on to other commissions, namely the Mona Lisa.
Speaking to the Italian newspaper Corriere della Sera, Carlos Pedretti, professor emeritus of art history at the University of California, Los Angeles, said, "There are no doubts that the portrait is the work of Leonardo," adding "I can immediately recognize Da Vinci's handiwork, particularly in the woman's face."
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However, whilst carbon dating conducted in a laboratory at the University of Arizona has placed the painting's origin between 1460 and 1650, Dr. Matthew Landrus, a research fellow at Oxford University and a member of the Leonardo Da Vinci Society, said it was highly unlikely that the piece was by Da Vinci.
"My initial reaction was no way, it can't be," he said. "There is no historical documentation for this kind of portrait being available. That said, one could always argue that it just wasn't recorded." Landrus said that he had spoken to many Da Vinci experts, like Professor Martin Kemp, and there was a belief that perhaps Pedretti had been misquoted by the Italian newspaper, as to be so confident it was a Da Vinci was a bit of stretch.
"What we don't have,"he added, "which is very typical with these types of attributions, is a decent photograph. Even with the small one that we do have, the finger in the painting is a bit odd. It's sort of pointing in a more emphatic nature that Leonardo would not have favored."
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Landrus argued that it could perhaps be a copy produced by one of Da Vinci's apprentices, such as Francesco Melzi, Giovanni Antonio Boltraffio or Gian Giacomo Caprotti da Oreno, better known as Salai. Landrus added, "There's also a French character to it, it could be from the French school. It could date as late sixteenth century, which would mean it came many years after Leonardo's studio work."
While Pedretti's statement did say that he needed a few more years to be sure which parts of the painting were by Da Vinci's assistants, Landrus said that even though the painting was probably not a Da Vinci - but was still worth around £50,000 ($80,000) - it was still a key discovery for Da Vinci experts.
"This is where Leonardo studies are going: what happened after him," Landrus said. "This is still very important: we get a lot of information as to what's happening in the sixteenth century after Leonardo, especially in the Milan school and southern France.
"How the media deals with that is the issue. This Italian newspaper is playing a little loosely with the information. That does add to the fun."