Zenith marks its 160th year with two Defy Zero G watches, each measuring 46mm and cased entirely in sapphire. Only ten of the blue sapphire version exist and only ten of the clear version. Every piece costs CHF 200,000. Inside each watch sits the Gravity Control unit, with the escapement mounted in a tiny double frame cradle that always remains horizontal no matter how the wrist tilts. Instead of letting rate errors cancel one another out the way a tourbillon does, the unit prevents the errors from appearing at all.
The idea copies the gimbal mounts that kept marine chronometers level on pitching ships. Zenith miniaturized the concept so that only the regulating parts self level while the rest of the movement stays fixed. Tiny weights inside the module shift until the escapement lies horizontal. The watch needs adjustment in only one position and runs more accurately as a result.
The first Gravity Control unit debuted in 2008 after seven years of work. By 2018 Zenith had trimmed its size by 70 percent. The present unit occupies 1.3 cubic centimeters and holds 139 parts, among them nine ceramic ball bearings that run dry. Conical bevel gears feed power from the barrel into the module through a miniature differential, keeping drive force steady even while the cage rocks.
The skeletonized El Primero 8812S beats at 36,000 vph and runs for 50 hours on full wind. A silicon escape wheel works with a nickel silicon pallet fork. The balance carries a double arrow regulator designed by Zenith chronométrier Charles Fleck. The module counterweight receives star pattern engraving that suggests a celestial body.
At 12 o’clock a lapis lazuli disc flecked with gold pyrite shows the off center hours, minutes and small seconds. Because the stone is natural, no two dials look alike. Rhodium plated facets on the indices hold Super-LumiNova. A power reserve gauge sits at 3 o’clock. The watch rides on blue alligator leather backed with rubber and closed by a titanium folding clasp. The limit of ten per color and the CHF 200,000 price reflect both the intricate mechanics and the difficulty of cutting a full sapphire case.
