Five years after Sotheby's sold an Old Master painting for about $10 million, the auction house concluded the work was fake -- andreimbursed the buyer.

Sotheby's earlier this year became aware of a possible authenticity issue with a 17th century Dutch painting attributed to Frans Hals and informedthe purchaser, the auction house said in a statement Thursday. It then hired an outside firm to conduct a technical and forensic analysis of thework, which was peer reviewed. Those efforts showed the painting couldn't have been created in that period because modern materials were used.

"Unfortunately, this established that the work was undoubtedly a forgery," Sotheby's said. "We rescinded the sale and reimbursed the client infull. Clients transact with us because they know Sotheby's will keep its promises when problems arise, and we were very pleased to do that in thiscase."

The disclosure demonstrates the sophistication of today's forgers who have fooled top art world experts, said Richard Feigen, an Old Master artdealer in New York. The discovery will also make auction houses and appraisers more discriminating when evaluating art, he said.

"It's one of the biggest scandals in my memory," said Feigen, who opened his gallery in 1957. "It's going to make people very wary, extremelycareful about things they are offered and the sources of those things."

Feigen said the fakes were very sophisticated. "There's nothing to my recollection on this scale and with this variety of artists," he said.

The blue marble-like surface of lapis lazuli makes it very difficult to determine the age of the work, he said. Gentileschi "did paint things onother surfaces, like copper and slate," Feigen said. "It would not be impossible that he might have used lapis."

Whatever the materials, the discovery of this forgery will change the art market, he said. "If all of a sudden something pops up, with no history,and they appear in no literature, people are going to be super careful," he said.

To read the complete article, see:
Fake Old Master Sold for$10 Million Rocks Art Market (www.bloomberg.com/news/articles/2016-10-06/fake-old-master-painting-sold-for-10-million-rocks-art-market)