From the research I have done, "Full" ceramic bearings (not to be confused with the "Hybrid" ceramic bearing) are not appropriate as an IMS bearing, but I bought one of these "inexpensive" full ceramic bearings (from the great land of China) mostly to study the cage, which is PTFE (Teflon).
Anyway, what a wonderful device. I was absolutely amazed at how light it is, but the way it just keeps spinning and spinning when you give it a twirl. No lubrication, and so smooth you think it has an air cushion instead of balls.
It is a 608, which is very small (about the size of a dime). But that made it even more amazing since it has so little mass, the way it keeps spinning and is so smooth.