Swiss agate and gold filled open faced lever watch Circa 1930

In case formed from a single piece of black agate with white bands by Zenith
–
A fine and rare Swiss agate and gold filled open faced keyless lever pocket watch, circa 1930. Rhodium-plated movement, damascened in a geometrical pattern, 17 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, and cam-type patented regulator. White enamel dial with fancy Arabic numerals, outer minute track and blue Arabic 24-hour numerals, sunken centre and subsidiary sunk seconds, original black Breguet hands. Case formed from a single piece of black agate with white bands, gold filled reeded bezel and pendant.
–
Diameter: 51 mm
–
Signed: Zenith Swiss