I've had experience with several Signature Engraving machines, which
model did you have in mind?
It's very versatile if you get the extras. I have a friend with a
laser engraver so I've had some, limited, experience with it. Though
it is speedy it isn't good at engraving metal, in some cases, eg.
stainless, you only get a coloring, not a real cut in the metal. And
doing the inside of a ring, I don't think he can but it might be he
just doesn't have the fixture.