I'm not a watch expert and have an Omega Certified Constellation chronometer that I bought then had overhauled by a reputable company, Universal Watch & Jewelry in Birmingham, MI USA. It's SS w/ a very thick gold top, white original dial with correct markings, and has the gold observatory logo on the case back.
It's a caliber 712 with 24 jewels, indirect center seconds hand, no other complications. According to a book I have by Heinz Hampel, the movement is only 3mm thick and it's circa 1967 (when you look at the watch, you wouldn't know it's a mechanical autowind, it looks very modern.
I wear this watch about once a month and all I have to do is give it a shake to start it and it runs perfectly all day and is still running the next morning when I put it back in it's box. It must have a very interesting movement because you can't even feel the rotor moving.
This watch seems to be an example of a very advanced design by Omega that pre-dates the negative effect of quartz movements on the industry shortly afterwards.
How could I find out more about this watch in terms of it's relative rarity and potential value? I added a few pix below.