WD-40 removes permanent Sharpie. I wrote on a door thinking I would change the door. Nope, we painted instead. WD-40 removed the heavy black marker without damaging the underlying paint.
I would definitely try this. WD-40 works on non porous surfaces, so if the dish is glazed ceramic or pottery, it should work with no damage. Be careful if there is any type of gold leaf on the plate, though. Don't know if WD-40 will hurt it.
Good luck. Please post a photo of the clock when you are finished making it. I'd love to see it.