Yep. Sorry to say it's not a genuine Omega, it has the crown from another brand and Omega did not mark the exterior of their case backs with hallmarks in that way. That is usually the easiest way to identify a fake.
And while it has a nice "hallmark", it's usually just gold plate over base metal.
If you get a pen knife and pop the back off I'd be amazed if it had an Omega movement.