Mariah Carey ’s boyfriend James Packer knows the way to her heart is putting half a mil worth of rocks on her chest. Packer gave Mariah the hookup Wednesday night — it’s an 18 karat yellow heart-shaped diamond. We’re told he gave to her right before she went on stage for her Vegas show at Caesars Palace — which explains the shout out she gave him. Carey thanked JP for “a new heart” … right before she sang “Hero” that night.
