It’s been very quiet in the world of the lost Leonardo that scholar Martin Kemp believes is a genuine Leonardo. It has sold in recent years for five figures but would be worth nine if the attribution sticks. For a while, authenticators claimed to have found Leonardo’s fingerprint on the work until David Grann demolished that expert’s reputation in the New Yorker. Now Kemp is back with further proof that he says nails the authenticity, according to the Guardian:

“Assertions that it is a forgery, a pastiche, or a copy of a lost Leonardo are all effectively eliminated,” Kemp told the Guardian. Earlier this year, he embarked on what he describes as a “needle-in-a-haystack” search for a 15th-century volume with a missing sheet. A clue lay in the stitch-holes along the portrait’s left-hand margin, suggesting it had been torn from a luxury-bound volume. But the chances of this volume surviving 500 years were remote, and the chances of it being found even remoter.

Against the odds, Kemp tracked the volume down, to Poland’s national library in Warsaw; the stitch-holes are a perfect match for those on La Bella Principessa, a portrait in ink and coloured chalks on vellum. It is overwhelming evidence, Kemp says, that the portrait dates from the 15th century – and not the 19th century, as Christie’s thought when it sold it in 1998 for £11,400 (it could fetch £100m as a Leonardo).

Kemp travelled to Warsaw with a specialist who has undertaken scientific analysis of the Mona Lisa, scanning beneath paint layers. Recalling the moment they opened the volume, Kemp says: “Yes, lo and behold, we could identify that there was a page clearly removed. The stitch-holes matched, the vellum matched. It is indeed 1496, it is indeed Bianca and indeed for her marriage. It’s uncanny. You could say: ‘Stitch holes are always the same distance apart.’ But the irregular stitching was spaced by eye, not precisely measured.”

Is This Portrait a Lost Leonardo? (Guardian)