Paintings by Han van Meegeren (1889-1947) at the Boijmans Van Beuningen Museum in Rotterdam on May 11, 2010. Van Meegeren became known for his forgeries, particularly of works by Dutch master Johannes Vermeer. Robin Utrecht | AFP | Getty Images Art forgeries are more common than you might think, but stories about them often stay underground.

That's according to lawyer Helen Mulcahy, a partner at legal firm Fieldfisher who specializes in art and fraud. "They often don't come to light," Mulcahy told CNBC by video call. "Reputation in the art market is so important .

.. not many people like to go to court," she said.

Cases are often settled in private in part because of the "embarrassment factor" for a buyer. Mulcahy advises wealthy clients on the checks they need to make when buying art, including attribution and provenance — namely, who has owned an artwork and when and where it has exchanged hands. Such information is detailed in exhibition records, auction catalog references, certificates or other documents .

"Provenance also should describe the medium, the dimensions, the date it was made. And sometimes it's not always the artist, it might be attributed to the artist, it might be the school, the circle of, so there'll be sort of levels down," Mulcahy said. Checking provenance is relatively straightforward on the primary market, where collectors buy from a living artist's studio or representative, but less so on the secondary market, which refers to the resale of works.

Buy.