Grandmother’s Omega: need help identifying

You might want to start looking at vintage advertising to see how Omega positioned their watches. I don't have any leads on where to look.

@X350 XJR knows more about these than almost anyone and your semantics are obnoxious IMO. I know who I believe, but you have no idea whose opinion is credible. The continuous questions with incomplete information are getting silly. The experts here are trying to help you, but you need to listen, not argue.

If you want definitive information then get the case opened and show the serial number on the movement and the inside case markings. Not everything can be done over the internet. Until then, you'll just be getting more opinions from people that you don't know. I know that you don't have the watch in your hands, but there's no rush. The information won't help you anyway since you will have no idea what crown to buy. When you get the watch and take it to a good watchmaker for servicing, he will replace the crown if that's what you want.