DIAMONDS ARE FOREVER: Barneys New York threw Los Angeles jewelry designer Irene Neuwirth a party at Chateau Marmont’s Bungalow One Tuesday night to celebrate the exclusive launch of her diamond collection. “I know it’s the opposite of what everyone else is doing, but I’m going more high-end than low-end,” she said. “My customer base has been asking me for diamonds for a long time and I’ve made several custom engagement rings.” One such sparkler caught the eye of Neuwirth’s longtime pal, actress Busy Philips, who was already married. “Irene wouldn’t let me have the ring, understandably since it was another woman’s engagement ring, so my husband ordered me one for our anniversary instead,” she said. The rest of Phillips’ bling was borrowed, as were the pieces worn by guests Courteney Cox, Sarah Chalke, Michelle Monaghan, Anna Faris, Erika Christensen, Angela Kinsey, Kate Flannery, Lauren Graham, Mia Wasikowska, Mae Whitman, Nia Vardalos and Mindy Kaling. “Don’t disqualify me from any gifting,” said Jenna Dewan as she eyed the jewels on velvet trays held by tuxedo-clad waiters.