Good idea OneWetKnee. Jollyone, what is the inside diameter of your crown? Knowing the size will help to determine if it could be a napkin ring. Most of them range from 1 1/2 to 2 inches inside diameter. Breezie
Coming from a mechanical background, it looks like a ring to keep space between ball bearings. It seems too crude to be anything of a jewelry or decorative nature.
I know that there are some that are made of a lighter guage of metal too.