oh, get it now! yeah, jade is a very hard stone. if you're trying to cut discs similar to your leather ones, it would take a lot of work, especially for an inside cut. i'm thinking that this would work as long as you put a rubber spacer between the inside of the jade discs and the handlebar itself, and made sure it wasn't a tight fit.
The Dremel will work, but isn't going to be easy, and you'll want diamond bits, etc... and you'll need to wet-cut the stone. UGH i feel bad for you because it would take you forever... :-\ PM me if you like and we can figure something out if you'd like me to cut them for you.
**edit - i was looking at the slab of jade again. is there enough space on it to cut out your discs without one of the cracks getting in the way? the stone would definitely split along those cracks, sooner or later -- usually sooner/during cutting.