The Gruen Watch Company was founded in 1894 and produced high-quality mechanical pocket and wrist watches until 1958, when the company failed. Under different ownership it continued producing mechanical watches until 1976. Gruens are produced today as inexpensive quartz watches by M.Z. Berger & Co. of New York and have no connection with original Gruens. As a consequence, virtually all true Gruens are vintage mechanical timepieces that require a delicate hand. The differences between setting a 1930s Gruen Curvex and a modern Gruen quartz watch are negligible. Setting a Gruen watch is a simple task but requires care.
Pull the crown as far as it will go and move it clockwise or counterclockwise to the desired time; this method is for a modern quartz-powered Gruen. If the watch features a date, pull the crown to the second stop and rotate the crown clockwise to the desired date. Then push in the crown.
Set the moon phase on a modern quartz-powered Gruen. Determine when the last full moon occurred, and rotate the crown to set the full moon image in the moon phase window, along with the date and time of the last full moon. Then advance the hands until the current time and date are reached.
Pull out the crown and set the hands to set a vintage Gruen watch; these have only hands and a sweeping second hand or subsidiary second hand. It’s best to rotate the crown clockwise, the natural movement of the hands, instead of backwards.
Wind your mechanical Gruen watch daily to ensure that it keeps time. With the crown flush against the case, gently rotate the crown clockwise and counterclockwise until it stops. It’s now fully set. Setting a Gruen watch and ensuring it keeps time for years requires daily winding, even if the watch is not worn daily. Wind it at the same time every day to ensure that the movement is fully lubricated and the oils do not congeal.
If you wear your Gruen mechanical or automatic watch daily, set the time and wind it when it’s off the wrist to protect the stem. Wind it each morning to ensure consistency in performance.
Some Gruens are automatic or self-winding. These watches are set by twisting the crown, but they don't need winding if worn daily. If the watch is only worn occasionally, it should be wound after not being worn for about 36 hours.
Service your watch every four to five years.
A vintage Gruen watch, like any old watch, wears over time, and the case may not seal properly. The watch should be kept in a clean, dry environment, like a wooden box, to protect it from dust, with its crown not touching or jammed against other objects.