Info on Universal Geneve watch

Dropped off a couple of old watches for service. Was searching online for similar watches to get details on them. Found some info on the Omega (1958) and attached pics from watch service guy. Dont have pictures of the UG interior. Will ask for them but may take a while. Surprised I cant find a similar one online. Its solid 18k gold. Didnt take picture of back if case (may have been number stamped there).
These belonged to my late father. He purchased the UG in Manhattan in the 1970s. The Omega was purchased in France.
Was looking through posts here and figured may as well post pictures. Have gotten interested in vintage watches recently so pulled these out of my drawer to service and wear. Any feedback here on them is greatly appreciated!

Hello Orion, my best guess is that UG is a ref. 142100 or a slight variation.

It's a nice thin manual wind watch, and if it is that reference it should use a caliber 42 (or slight variation).

Sometimes they have the reference number and serial on the back (generally if the watch case was made in Switzerland). If it was made in Switzerland, there should be a poincon de maitre on the inner case back which should also show who made the case.

If the case was made in the US (as often happened in the midcentury due to tariffs) then there should be a number on the back that I believe references the US serial number (which is distinctive from the overall serial numbers). Generally this number is often 5 or 6 digits.

Happy to try to answer specific questions you might have.