Can you tell me how you adjust the size of the ring in relation to the finger, when you want to enlarge it to a larger size or patch it to a smaller size.
Do you start with a specific finger size and a specific thickness?
are talking about fully modelled geometry with all sorts of bling and details? if you want to have full control you would have to dive into grasshopper then.
what rhino can give you right out of the box is history. for instances a ring can be made out of 2 curves constituting the size and the thickness. when you sweep the structure you can adjust the size and thickness of the ring with the input curves. for size you would have to scale it where the profile meets the rail.