Looks fine. If it’s a fake, it’s a good one—that’s probably the best anyone can say here.
This would not be a challenging part to counterfeit—the packaging least of all—and whereas the cheapo knockoffs have shoddy Omega symbols and poorly etched part numbers, it would appear there are now many sellers offering much better looking ones that are almost certainly Asian-mass-produced fakes. If you got a great price and it’s indistinguishable from the real thing, maybe it doesn’t matter that much?—just be honest with any potential buyer that you’re unsure of its authenticity if you ever decide to sell it—?
I suspect that when it comes to little bits like this, nowadays, the only way to know for sure that it’s real is to purchase it from Omega. eBay is the Wild West.