In 2007, Cartier came out with their Ballon Blue collection. Its unique feature is the recessed crown that leaves a small 'dent' on the dial. The case has a smooth, round shape like a pebble. The WE900651 model has a white gold case with a diamond-set bezel and a silver dial. It runs on the self-winding caliber 049 (without a date) and has a leather strap.