Step bezel visibly raises thinner cabochons above the “surrounding
terrain” of backing metal. Step bezel has a shelf of metal on the
inside that the bottom of the cab rests on. The visible outside may
or may not have surface ornamentation.
Speaking selfishly, Indian Jewelers Supply offers two plain step
bezels in 14k yellow, and four more ornate versions in sterling
silver.
Step bezel can be created by you, utilising an interior of square
wire on the desired bezel. This is handy where you only have a very
infrequent need for the services of step bezel.
Good luck!
Dan Woodard.