Need Help Identifying (Presumably) Omega Seamaster 16203

Hey guys! Hope you're all doing well.

Long story short, a few years ago I inherited what appears to be a vintage Omega Seamaster from my grandfather (it seems to be a common situation on this forum). The crystal was in pretty bad shape and eventually came off. There's a small number, 16203, on the back. I'm attaching some pictures here.

Would you be able to help me confirm whether this is an original watch? I'd like to replace the crystal and strap. There's quite a bit of patina on the dial, but I don't mind it at all—in fact, I find it charming. 😀

If it is an original Omega Seamaster, would you be able to tell me the exact crystal size I need to buy? I live in Brazil, and there don't seem to be many specialized shops here, so I would probably need to order it online from abroad.

Thanks a lot!

I am afraid I will have to disappoint you, but I think it might be a fake watch. Open the back cover and examine the movement. I guess you will find that the movement is not omega.

Hi prokudin, thank you for your reply! I watched a few different videos online, but I'm afraid I still can't tell. I'm attaching a few more pictures and a short video here.

This is unfortunately a fake watch

The watch is indeed a fake one. However, given it was your grandfather's, it does have sentimental value. If you keep it, find a watchmaker to change the crystal and perform a basic service and wear it. Just keep in mind that you will not be able to sell it as a genuine Omega, so do not invest much in it.

Thank you very much! I'll follow your advice.