Suri Cruise isn’t the only celebrity child who’s charming Hamptons residents this summer.

A local mom was gobsmacked on Monday when she went to Ralph Lauren in East Hampton, where her 3-year-old daughter bumped into the adorable first daughter of hip-hop, Blue Ivy.

“The woman overheard her daughter chatting with someone,” said an East End spy. “When she looked over to see who it was, her daughter was speaking with Blue Ivy and Beyoncé.”

The source added Blue Ivy, 2, was “telling the other girl she was shy.” Jay Z then joined the conversation, and “couldn’t have been nicer, asking the other girl how old she was.”