Watches: My 1949 Omega COSMIC MOONPHASE

Omega made these watches between 1947 and 1956. These were powered by a cal 27 DL PC AM, which was later renamed as cal 381 in 1949.

27 refers to 27mm in diameter; DL refers to the complication of day, date, month and moonphase; PC means that the movement is shock absorbent and AM refers to its anti-magnetic properties.

Info that I got states that Omega had a total production of 50,000 for this movement. This movement has 17 jewels and is manually wound. It is not a true perpetual calendar because although the day, date, and moonphase change automatically as long as the watch was wound, the month needs to be advanced manually by pressing an indented button located in the 4 o'clock position at the side of the case. The pointer date and moonphase are also adjusted through indented buttons at the 2 o'clock and 8 o'clock position. The day is adjusted via winding the hands past 12 midnight. I've posted pics of the recessed buttons at the side.


This model had a number of dial styles, the most common are steel models with printed numbers or hour markers and logo. These don't seem to age well and many of those that I looked at that were for sale had been re-dialed. I have read in some forums of a black dial version with a red date pointer hand but I have yet to see one.



The movement for my watch dates this to 1949 and is a cal 381. The dial has applied numbers and an applied Omega logo. It has a 14k gold bezel and stainless steel case. Original models when they came out in the late 40s had a pigskin strap but this one came with a brown leather strap. It also displays the Day and Month in Spanish. Per Omega, parts are no longer available in stock for English Day-Month displays.

There is a square cased version (case ref OT 3944) and this one is most prized by collectors. The place I purchased my moonphase from had this version for sale but it was way too rich for my blood. The square case version has been re-issued by Omega as part of its limited edition Museum Collection.