Back to IGS | FAQ | Contact

Cabochon with rounded bottom?


Hello! I am fairly new to purchasing finished gemstones, and I received one recently that surprised me. It is an Ethiopian Opal cabochon, about 7mm x 8mm x 5mm high. The bottom is not flat, but somewhat rounded. Do you know why it would have been finished this way?

I’ll have to either flatten it or figure out how to bezel set it with some kind of filler to keep it stable in the setting…


That seems to be pretty common now. I’ve gotten some rubies and sapphires like that.


So makaturquoise, do you flatten the bottom or set them with some stabilization method?

(If I flatten it, I’m concerned about opal, which is soft and brittle…)


If I might chime in, u dont modify the stone, u build a setting to show the stone to the max. If u like ur stone why modify a touchy stone to begin with. Im posting 2 pics of my opal in a setting built by my jeweler, 18kt gold , yellow, & very well finished. Opal is rare & if u have a nice one, show it!-b careful-steve…


Yes, I agree the setting in the photo is best for your type of stone (rounded bottom) and also what I use most. If you don’t want that type of setting you can set it in a bezel with or without a backing, or one with a backing that has a hole in the center (of the back). If you set in a bezel with backing, set it in cornhusk, but don’t flatten the back under any circumstances, no matter the type of stone.


Thanks for all the input. I agree, it doesn’t seem advisable to alter the back of this finished stone! I ordered this stone for a particular project, which needs a closed back. I contacted a different seller, and am actually ordering another stone (that definitely has a perfectly flat back) for my project - so that frees up this stone to be set with prongs…
I really appreciate the input.