onyx. It has that black, shiny but not metallic sheen.

This is a guess from years of working for a RenFaire jeweler who sometimes doesn't sort out his new merchandise when we need to put it into displays... we try to keep similar stones that have close color values (like amethyst and garnet, hematite and onyx) in different cases so it's easier to explain.

I like the ring base. It's purty.

I'd have to see it in person to determine the onyx/glass thing But that ain't going to happen soon.