Jay-Z threw an intimate party to celebrate wife Beyoncé‘s 29th birthday on Saturday. He took over nightlife im presario Scott Sartiano‘s and Richie Akiva‘s about-to-open Chelsea restau-rant, The Darby, and invited friends including Al icia Keys, Serena Wil liams, Kanye West and Sean “Diddy” Combs to toast Beyonce . . . while DJ Cassidy took over the decks. A spy reports, “Jay brought a six-layer cake out for B, they were really affectionate. Cassidy played Stevie Wonder‘s ‘Happy Birthday.’ The party went on until 6 a.m. Both Jay and B’s moms were there, but there was no sign of her father or her sister. Diddy was the last to leave. Jay filled the room with orchids.”