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.