GMT NERO GMT or Greenwich Mean Time used to be the standard on which all timezones were based. Nowadays GMT stands but for one timezone and has lost its original function to UTC or Coordinated Universal Time. Our diving watch GMT uses a special Swiss Made quartz movement that indicates a second time zone with a distinctive additional hand. Water resistant to 200 meters and with a heavy duty stainless steel case the iconic GMT comes with a stainless steel bracelet or a silicon strap and is available in a black PVD plating, too