Indonesian blue opal petrified  wood .. ring 
This is a lovely little teal shade petrified wood cabochon!  Fine silver bezel setting with sterling silver droplet double ring shank.
Size 9
Blue Opal Wood
Indonesian Blue Petrified Wood is from ancient teak (hardwood) trees that turned to stone. The Blue Petrified Wood is from trees approximately 20 million years old. Minerals present in the mud and water prior to and during the petrification process leached into the wood giving it color.
Petrified Wood comes from the Greek root petro, which means rock or stone, with literal meaning ‘wood turned into stone’. It’s the name given to the fossilized remains of terrestrial vegetation.