I had two rings made, one for each of my daughters. The jeweler used just the top (crown?)
of the ivory. The shape was sort of oval-like, with the surface of the ivory flush or slightly above the gold ring. Not gaudy at all; a beautiful ring. This was about 9 years ago, I think I paid about $225 per ring.
As I recall the jeweler had to do the work after hours, because the grinding of the ivory had a pretty bad smell to it. Wish I could post a picture for you but neither ring is available to me. I would do it again, they turned out beautifully.
Gary