We are sure of nothing, and if Leonardo participated, it’s not for all the drawing, but for some parts of it,” Mr. Deldicque said. He added that although the drawing had a similar composition as that of the original Mona Lisa, exhibited at the Louvre, the Monna Vanna was a parallel art piece and that the two were distinct.
The sketch was originally attributed to da Vinci when the Duc d’Aumale, the son of France’s last king Louis-Philippe, bought it in 1862 for the Condé Museum’s collection.
But further analyses in the early 20th century led experts to the view that a student of da Vinci had drawn it, although the creator’s identity remained uncertain. The museum’s curators decided to conduct extended tests on the sketch after new preliminary research, and ahead of the 2019 exhibition, Mr. Deldicque said.
Other experts found the potential attribution plausible.
“Very often, drawings are resumed, completed, transformed,” said Patrick de Bayser, an expert in old drawings who works at the Galerie de Bayser in Paris and helps auctioneers value these drawings.
Mr. de Bayser, who helped discover a da Vinci sketch of St. Sebastian in 2016, said that although it seemed unlikely that the entire composition was by da Vinci himself, testing would help uncover more details about each layer of the drawing, and help determine whether the original one was from da Vinci’s own hand.
Scientists have managed to date the Monna Vanna to around the start of the 16th century, which matches the lifetime of da Vinci, who died in 1519.
Analyses have also showed that the paper used for the drawing was from the area between Florence and Venice, but a Louvre conservation expert, Bruno Mottin, told the newspaper Le Parisien that he would be cautious about attributing the Monna Vanna to the Italian painter.
“The hatching on the top of the drawing near the head was done by a right-handed person,” Mr. Mottin said, adding that da Vinci was left-handed. Scientists have been unable to determine whether the hatches of the lower part of the drawing were done by a right- or left-handed person.
“Monna Vanna’s hands look very similar to the hands painted in the first version of Mona Lisa” Mr. Deldicque said.
The Renaissance master is said to have painted the Mona Lisa around 1503. It depicts Lisa Gherardini, wife of Francesco del Giocondo, a Florentine cloth merchant.
Around 20 paintings of nude women that bear a resemblance to Mona Lisa are exhibited or stored in museums across the world. one of the most famous, the Dona Nuda, is at the Hermitage in St. Petersburg.
After experts at the Louvre have finished their analyses, the Monna Vanna is scheduled to be returned to the Condé Museum, where curators are negotiating to borrow some of these other paintings from museums in Germany, Italy and Russia, with the hopes of displaying them for the 2019 exhibition.
“So many students of Leonardo have painted naked Mona Lisas or written about it, that we are almost certain that Leonardo painted one,” Mr. Deldicque said.
And although scientists may come up with the first conclusions around the “nude Mona Lisa” in the fall, Mr. Deldicque said that he wanted to keep some mysteries for the exhibition.
“At least both the Louvre’s Mona Lisa and the naked Mona Lisa have one thing in common: They will always keep a lot of mysteries,” Mr. Deldicque said.
