genuine opal doublet gemstone is set in a handmade sterling silver solitaire ring. The opal is 1.5 carats and is mostly blue with flashes of green and red throughout, A pretty opal Ring size is 7 comes with black velvet gift box An opal doublet is a slice of precious opal glued to a black backing. This technique is used frequently with rare opal to produce larger and stronger pieces at a lower cost. The black backing, usually made of vitriolite or common opal, also causes the color of the opal to become darker and more vibrant