Quattro Teschi - Four Skulls Black Sapphire Wedding/Engagement Ring (#w005)'Quattro Teschi' Four Skulls Black Sapphire Wedding Engagement Ring LIMITED EDITION! Metal : s925 Sterling Silver Stone : Black Sapphire* (round cut ) What Is Black Sapphire? Black sapphire is a nearly opaque stone whose color is so dark that it appears to absorb all light that enters the gemstone. Because of its color, black sapphire is often confused with onyx. Indeed, this stone can successfully act as an onyx substitute. Although both stones look