A day & night indicator (normally) turns once in 24 hours. A simple day/night indicator can be a two-colour disc showing day or night through either white and black coloured segments. Mechanically the same as a 24 hour indication, one turn of a hand in 24 hours.

Deconstruction Dubois Dépraz Retrograde Seconds, GMT & 24 Hour Indicator module. Reference 15115.

An original multiple retrograde seconds animation module made by Dubois Dépraz, exclusively for Pierre DeRoche. The module calibre 15115 has 4 retrograde seconds hands which follow each other starting from twenty to the hour, until twenty passed, then break for 20 seconds. At six o’clock on the dial there is a second time zone (GMT) linked with a 24 hour day/night indicator which are both corrected from the winding crown.

Deconstruction Breguet Reine de Naples « Jour/Nuit » (8998)

An unusual ladies form watch with a day and night, 24 hour rotating disc encompassing the balance and escapement with the opposite side housing an engraved titanium moon. The watch includes hand engraving back and front, guilloché, unusual diamond setting on the inside as well as outside of the bezel. Mother of pearl and lapis lazulite. (Launched in 2013) Functions: offset minutes & hours with a 24 hour, day & night indication at 12 o’clock set with the balance and escapement.