This painting, called "Santa Rufina," depicts a patron saint of Seville, Spain

NEW YORK (CNN) -- A newly discovered work by Spanish painter Diego Velazquez will go under the hammer Friday at Christie's in the first public auction of a Velazquez in 29 years.

The painting, called "Santa Rufina," depicts a patron saint of Seville, Spain and was painted between 1632 and 1634. It hasn't been seen in public in more than 50 years, since it was sold in 1948 to a private collector.

"Any painting by Velazquez is very special. He is an artist who is considered of the utmost importance and therefore the utmost desirability, and his work is extremely rare," said Anthony Crichton-Stuart, head of Christie's Old Masters department.

The last Velazquez to be sold at auction was the portrait of "Juan de Pareja," which Christie's sold in 1970 for $5 million, at the time a world record price for a work of art. That portrait now hangs at New York's Metropolitan Museum.

This Velazquez is expected to bring a price of at least $3 million.

"He is so important and has always been considered to be so important that the vast majority of his pictures are in museums and there are very, very few left in private hands," Crichton-Stuart said.

Though "Santa Rufina" is not signed, that is typical for the artist.

Christie's has spent a year researching the painting's authenticity, conducting a scientific analysis and tracing the history of its ownership. Researchers even took the painting to Madrid's Prado museum so it could be compared to famous Velazquez works there.

The first recorded owner of "Santa Rufina," according to Christie's, was Velazquez's principal patron, Don Luis de Haro, who became Spain's prime minister under King Philip IV in 1643.

The painting disappeared until 1868, when it surfaced in the collection of Earl of Dudley in England. It was sold in London in 1925 and last seen in 1948 when it was resold to the present owner's family.

The Velazquez is part of an Old Masters sale featuring works by Spanish, French, Dutch and Flemish artists including El Greco, Franz Hals, and Pieter Breughel.

On Thursday, Christies auctioned Old Masters drawings for a total of $11.3 million.

The top lot, "Madonna del Popolo" by Federico Barocci, achieved one of the highest prices ever paid in New York for a drawing, Christie's said. Bidding yielded a final price of $2,642,500, which was just over the high estimate for the work.

Reuters contributed to this report.