green stone

Hi, I need help identifying this little Green pebble I found in Turkey It’s a regular green colour all over and smoothed by the sea it didn’t lose colourbasutbdried and is still a quite bright olive green colour Can you help?

I recently bought this ring and am trying to identify what it's made of. The seller said he dug it up, as is, in North Georgia USA. He polished it and set in stainless steel. Apparently, it was found in this circular shape when found.