The newly engaged star shows off a diamond sparkler at the Met's Costume Institute Gala in N.Y.C. Plus: Mariah Carey, Ashton & Demi, Clive Owen and more

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BACKED UP

Rihanna gets up close and personal to rocker Adam Levine during a Los Angeles video shoot Friday for the remix of Maroon 5's "If I Never See Your Face Again," hitting the airwaves on May 13.