This is a super rare gem silica natural ring. It is a mix chalcedony, chrysocolla. It is indosesia's most prized stone. 

I was lucky to have 4 of these made from some rough I  purchased. I kept one myself and love it..I never take it off. It is very comfortable and durable. I am super active and still it hangs tuff. 

If you want to research this material. It is also called Doko. Or Bacon stone. Kasiruta island, Indonesia.

Direct from the mine , cutter to me. 

Type: chalcedony, chrysocolla. Gem silica.

Color: green blue

Clarity: transparent

Weight: 12.88ct. 

Size: 7 -  O.D. 23.3mm. I.D. 17.1mm. 6mm. 3.1mm Thick

Origin: Indonesia