The ring has gone missing. I haven't sold it (I don't think you can), and I didn't give it back to Bates either. I've had in my inventory in Stillwater, but it's gone now.
I checked my quickslot bar and my followers inventory & equipped item.

This is a wild guess, but any idea where it could be, please? My main problem is that I use UAP 2.02 and I use the ring to spawn items...