[Help] Identification Square Gold Vintage

Hello,

I just inherited this vintage Omega. Please help me identify model / model number / year /. . .
I can't even find a watch with the same case shape.

It has been likely purchased in France between 1950 and 1970.

I tried to open it but failed and slightly scratched the back.
I'm not doing it any more harm and will take it to a local watchmaker.
I hope there will be some additional infos on the movement or inside the case.

Wonder what experts would say... 1) could be a fake 2) could be a localy made watch case. Usual in France, apparently. But I know nothing about watches....

99% the watch it's not fake..usually i seen the "De Ville" model has no more info on dial. Of curse you have to go to an watchmaker and open the watch for more info. Regards.

I dropped the watch at a local watchmaker for service.

Well done! According to them, the case is definitely a "french case" and the dial is 18k gold too.
It seems to be a locally made watch except the movement.
Inside the case there is a Omega logo ans some serial number.

The movement is a calibre 620 and is in good shape.
The watchmaker also told me that the watch is from 1964 despite its style looking more like a 1940s or 1950s watch.

Apparently there was some Omega facilities in France at the time and it is common in France to see some "unkown" models like this one.
He told me that back then, gold was too expensive to import so French facilities would make their own 18k cases.

I can't wait to get it back, its only 23mm large but it's super classy.
Thank you all for your answers.