LONDON – Verily, it’s a Vermeer.

Christie’s auction house says science has confirmed that a disputed painting is the work of Dutch master Johannes Vermeer. The painting could fetch 8 million pounds ($13 million) when it is sold next month.

“Saint Praxedis” is believed to be the earliest surviving work by the 17th-century artist, but there has long been a question mark over its authenticity.

The work was tentatively attributed to Vermeer after it appeared in an exhibition at New York’s Metropolitan Museum in 1969, and the authorship was reinforced in 1986, when leading Vermeer scholar Arthur Wheelock argued it was authentic.

But other experts remained skeptical. The painting was not included in a “Young Vermeer” exhibition in The Hague in 2010, but was displayed in a 2012 show of the artist’s work in Rome.

Christie’s said Friday it was declaring the work a Vermeer after scientists at Amsterdam’s Rijksmuseum and Free University carried out isotope analysis on its lead white — a coveted but toxic type of paint made with lead and vinegar.

“They’re able to basically DNA test lead white,” said Henry Pettifer, Christie’s head of Old Master paintings.

The tests found that the lead white was a precise match for that used in another early Vermeer, “Diana and her Companions” — “So precise as to suggest that the same batch of paint could have been used,” Pettifer said.

He said the research, along with analysis of the date and signature on the painting, amounted to “a compelling endorsement” of Vermeer’s authorship.

Praxedis was a Roman Christian who cared for the bodies of religious martyrs. Vermeer’s painting shows her as a young woman, grasping a crucifix while wringing blood from a sponge into a vessel.

Doubters point out that the painting is a near-copy of an Italian work, and its religious subject is not typical of Vermeer, best known for paintings rooted in daily life, such as “Girl With a Pearl Earring.”

But Pettifer said Vermeer was a self-taught artist who had recently converted to Catholicism when he painted “Saint Praxedis” in 1655, aged 22 or 23.

“All of these things stack up for the case,” Pettifer said. “For a self-taught artist to make copies is what you would expect.

“I think this will force another look at the early paintings of Vermeer.”

The painting — one of only two works by the artist in private hands — is due to be auctioned July 8 as part of the collection of Barbara Piasecka Johnson, a Polish-born art-lover who amassed a huge trove of art after marrying Johnson & Johnson heir J. Seward Johnson. Piasecka died last year, and proceeds from the auction will go to her charitable foundation.

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Online: www.christies.com