Sterling silver, 22K gold, Australian boulder opal. THIS RING IS ADJUSTABLE!! This is a really pretty opal, blues, greens and violets run all around the stone.  The stones setting itself measures 1-3/8" long by 3/4" wide.  It is a size 7-1/2 but I can adjust it for you, up to an 8-1/2. The band is 12MM (1/2") wide at the bottom, an easy ring to wear. I WILL ACCEPT RETURNS UP TO 10 DAYS FROM RECEIPT & I WILL PAY THE RETURN POSTAGE01