There are quite a few ways to approach this ..... but this is the easiest to start with
use the five axis option buttons ( you do not need a five axis machine to use the drive surface options as long as the drive surface is flat and or curved in the fourth axis ) think about a sleeve around your ring anything in the shadow of that sleeve will be cut to the chosen depth.
This drive surface can be anywhere in the 360 degrees around the part and it can be shaped to cut only what you want ..... like inside a hole
or inside the bezel on a ring
There are plenty of videos on how to create a tool path with drive surfaces