Art collector Hester Diamond — who just happens to be Beastie Boy Mike D ’s mom — has given quite the painting to the Worcester Art Museum. The work, Paolo Veronese’s “Venus Disarming Cupid” — which was worth almost $3 million when Diamond bought it at Christie’s — is a “high-level painting” that will round out the museum’s collection, explained Director Matthias Waschek . “We don’t have strong enough holdings of Venetian paintings in our European collection, so this really makes it a very important player for us,” Waschek said. He added (with a laugh) that the work is also a big deal for the museum because its other paintings are pretty G-rated. “Our collection is very much of a Yankee collection,” he said. “Now finally we have a luscious nude.” Up until now, the museum’s most revealing paintings have been “Woman at her Toilette” from the School of Fontainebleau, which features a woman wearing sheer veils, and “The Discovery of Honey of Bacchus” by Piero de Cosimo, which involves a festive scene with some under-dressed mythological creatures. Waschek said that Diamond decided to give the painting to the museum a few months after he paid her a visit. She was a social worker in the 1950s and her husband a public school teacher (he died in 1982 and she remarried) when they began to collect art, according to a New York Times article. They amassed an impressive collection, and when Waschek visited recently with Diamond’s stepdaughter, Rachel Kaminsky, who is a Worcester Art Museum board member, the piece caught his eye. “We had great fun and I was just flabbergasted by this Venus painting,” he said. “I couldn’t stop looking at it.” “Venus Disarming Cupid” will go on view Sept. 20.