The tiny ladies' watch form movement Zenith 57.8 was released in the late 1940ies in its predecessor version 57 (still with 18000 A/h) and was then relaunched in the 1950ies with the new beating rate of six half-beats per second.
The movement is a standard construction and still uses only 15 jewels, since at that time, it was not usual to bear the minute wheel in rubies.
As common on form movements, the mainspring barrel uses almost half of the available space and so ensures a relatively long power reserve and a constant, hopefully low, deviation rate all over the day.
The beautiful golden toned Glucydur screw balance in not yet shock protected, but already beats with 21600 A/h, which is pretty unusual for such an old and time movement. And were also not many movement swith screw balance available, which had a beating rate of more than 18000 A/h.
As excapement, there's the conventional swiss pallet lever escapement.
The decorations can not only be found on the movement side, but in reduced amount also on the dial side. Here, you can also see the yoke winding system.