Is it a Leonardo? Experts are split

For the second time in a century, a high-profile case in the New York courts is set to turn on the question, "How can you tell an authentic Leonardo da Vinci?" It's a more delicate matter than you might imagine.

Jeanne Marchig, previous owner of a drawing that went under the hammer at Christie's International, New York, in January 1998, is suing the auction house for "negligent misattribution."

"Christie's strongly disagrees with these claims and believes they are without merit," a spokesman for the London-based company said. "The continuing debate surrounding this work has seen a significant number of the world's leading academics and critics continue to cast doubt on the alleged attribution to Leonardo."

Cataloged as "German, 19th century," the work sold for $21,850 and was resold in 2007 for about $20,000, according to the suit. Since 1998, a number of leading authorities -- including Martin Kemp, emeritus professor of art history at Oxford University -- have identified it as a hitherto unknown masterpiece by Leonardo da Vinci. It has been estimated that, as a Da Vinci, the work is worth $150 million.

That estimate, given by Otto Naumann, a New York dealer in Old Masters, to Milton Esterow in the January issue of the magazine Art News, was "contingent upon uncontested attribution." That's hard to achieve in cases like this.

Counts of authentic Michelangelo drawings by renowned scholars vary from a conservative 30 to 40 to more than 700. What makes the difference? Evidence, of course, comes into it -- type of pen stroke, methods of shading -- but it also comes down in the end to opinion: the "eye" of the expert.

It's the same in the case of the disputed Da Vinci, dubbed "La Bella Principessa" by Kemp. The vellum, or treated animal skin, on which it's drawn is from 1440 to 1650 according to carbon dating. The drawing is by a left-handed artist, which Da Vinci was. A partial fingerprint on it is a match for another on a more definite Da Vinci.

Those are both subjective calls. Kemp answers a firm yes to both. He has, he writes in a book on the subject ("La Bella Principessa: The Story of the New Masterpiece by Leonardo da Vinci"), "not the slightest doubt" that this is "a masterpiece by Leonardo da Vinci."

Others are not so sure. Off the record, many in the art world express doubt.

The last big Da Vinci case in New York was in 1929. Then the plaintiffs were Mr. and Mrs. Harry Hahn, Franco-American owners, they claimed, of the authentic version of Da Vinci's portrait known as "La Belle Ferronniere." Questioned by a New York journalist, the Old Master dealer Joseph Duveen flatly stated that the authentic painting was the one in the Louvre and that this was a copy.

The owners sued for $500,000. Duveen marshaled batteries of experts, who fared badly when cross-examined in the witness box. Statements such as "the impression produced on my mind is that it is not by Leonardo" did not impress the court, the jury was hung, and Duveen eventually agreed to pay $60,000.

More than 80 years later, there's still no complete agreement about "La Belle Ferronniere." Most scholars believe the Louvre work is a genuine Da Vinci, with perhaps a little help from assistants. Some still have doubts about even that.