London (CNN) The 500-year-old painting of Jesus Christ that, after centuries of neglect, has been identified as Leonardo da Vinci's "Salvator Mundi", is a discovery so rare, so unlikely, that when New York art dealer & da Vinci expert Robert Simon first saw the painting, he didn't even consider the possibility.
"The whole idea that it might be by him was almost an impossibility; it's kind of a dream," said Simon. The painting joins a small collection of surviving paintings by the Renaissance master who lived and worked in Italy in the 15th century & has been carefully conserved to remedy the damage it suffered over the years.
"Salvator Mundi", (Savior of the World), is known to have been owned by English King Charles I before moving around various private collections until 2005, when the current owner brought it to Simon to study.
"It was a very interesting painting but it's not something I looked at and thought, 'Oh my God, it must be a Leonardo,'" said Simon.
The true identity of the 66 x 45 centimeter oil-painted walnut panel had lain dormant for years, its distinguishing features hidden under layers of crude over-paint. It was known to have existed from preparatory drawings made by da Vinci and copies by his followers but experts assumed it had been destroyed. There are only some fifteen surviving Leonardo paintings in the world and the last one to be discovered was the "Benois Madonna" more than 100 years ago.
So, what first alerted Simon and Modestini to the possibility that the painting they were looking at could be the real thing? The truth revealed itself little-by-little as Modestini painstakingly removed layers of varnish and over-paint in her studio and Simon carefully studied the painting's provenance, comparing it with da Vinci's other paintings and preparatory drawings. But there were two important clues. One was a so-called "pentimento," an alteration in the painting showing traces of previous work that Simon discovered by scrutinizing a photo of the painting taken using night vision, and using other techniques.
The other was the painting of Christ's curls."I was looking at the curls and St. John the Baptist at the Louvre, who has this huge head of massive ringlets and they are exactly the same," said Modestini.