Very unusual old poison ring, from when, where?

by Teresa
(Dana Point, CA, USA)

I've scoured the web, looked at hundreds of images, can't find anything like this ring I bought at an antique shop in town.

No markings that I can see, but I'm afraid to clean it, since the band looks like pale gold, and the rest is thin silver metal with some type of gold leaf on it. Hope that shows in photos.

The inside of the "box" is tarnished a bit, and one small section of the silver trim around the clear glass stone (?) is missing. The clear "gem" has a slight "point" on top, rather than being a smooth radius, and it has a rough edge where it is cut to fit into the top of the ring. Any ideas as to era, usage? Any help would be greatly, greatly appreciated. Thank you!