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.