A ring fit for royalty and worn on the pinky of hip-hop's crown prince is going up for auction. Originally a gift from Tupac's ex-girlfriend, Tupac wore the ring extensively, on stage and in the "All About U" music video. The letters M.O.B. stand for "Member of Blood", the notorious gang, and by extension, Death Row Records. The 14k gold ring with diamond M.O.B. letters is up for auction now — a piece of American music history.