Omega Constellation Co-Axial Watch - 27 mm Steel Case - Diamond-Set Bezel - Mother-Of-Pearl Dial - 123.15.27.20.55.00327 mm stainless steel case, transparent back, diamond set bezel, domed scratch resistant sapphire crystal with anti reflective treatment on both sides, White mother of pearl dial with a wavy pattern that flows between the iconic claws, 11 diamond indexes, date window at 3 o'clock, caliber 8520 self winding movement with chronometer and automatic winding in both directions to reduce winding time, approximately 50 hours of power reserve, stainless steel