After cleaning out my grandparents’ house years ago, we found this watch. I don’t know much about watches, alas. It’s Omega, and the outer ring has Roman numerals (bolded at 3, 6, 9, and 12), and the smaller dial has Arabic numerals at 15, 30, 45, and 60.

The face has a diameter of 3.5cm.

Any assistance would be appreciated!