I could not see a taper on the black ring until I held it up against a square and then I could see a very slight taper like the middle ring in your picture.
My other ring has a grey coating on the wearing surface but it does not look like chrome to me. Also it has a tiny 90 degree step at the top outer corner of the ring.
I talked to the service manager where I bought the rings and he said the black ring goes on top and the coated ring with the step is the middle ring.
