Perhaps 15 paintings by Leonardo da Vinci survive today, including the iconic ‘Mona Lisa’ and ‘The Last Supper.’

A newly-authenticated work by the Renaissance master  – known as 'Salvator Mundi ' or ‘Saviour of the World’ – has caused a sensation in the art world. It depicts the head and shoulders of Christ, and though 500 years old, after cleaning and restoration, is in remarkably good condition.

The painting was first recorded in the collection of Charles I in 1649, but a century or so later it seemed to have disappeared. In 1958, a painting with the same name, but greatly altered in appearance was sold from a private collection for £45.

A later owner decided to have it cleaned and that is when layers of grime and overpainting were carefully removed to reveal a lost treasure. Considered by some to be priceless, the work is currently valued at £125 million and is owned by an American consortium.

In an upcoming TV special, CNN talks with Robert Simon, an old masters dealer acting on behalf of the painting’s owners, and to Dianne Modestini, the restorer who brought the painting back to its original state. Click here for show times.

The painting will be shown in the context of the master's other works in the highly-anticipated Leonardo exhibition at the National Gallery in London, from November 9, 2011 – February 5, 2012.

The last time a Leonardo painting was discovered was in 1909, when the Benois Madonna, now in the Hermitage in St. Petersburg, came to light.