A tipster who was at the Chelsea gentlemen’s bar Barracuda* on Saturday night ran into the designer’s on-again boyfriend, former hustler Jason Preston. He was “flashing a Cartier ring to his friends, telling everyone he was engaged,” says the snitch.

“Then out of nowhere Marc popped up, and they were all over each other, kissing and saying ‘I love you.’” Neither Preston nor Jacobs responded to inquiries yesterday about the Cartier band.