Lake County Fire Opal? comes from mines in Oregon; the stones display an even, saturated burnt-orange color. The brilliant color is ideal for a variety of jewelry designs. The color of fire opal is due to fine traces of iron oxide. This variety does not usually contain the flashes of light and color typical of other opals; like other opals, however, fire opal is composed of silicon and water. The Aztec culture held that a stone with this fire and beauty had to have originated in the seas of Paradise. Fire opal is the only natural opal that is normally faceted. Rio is proud to offer the American Mined? Collection, a growing selection of gemstones sourced from mines located here in America. These gemstones consistently present the excellent color, clarity and quality we look for in every stone we offer you. Each of these gemstones allows us to provide a clear, documentable path from the mine to your bench; you and your customers can be confident that every one is mined, cut and processed under conditions that meet all standards for worker safety, environmental protection and responsible production. The cushion cut is a classic style; it combines features of the oval cut with a deep cut and large facets. Specifications: Cutting Center : Germany Mineral source : Oregon, U.S. Brand : American Mined Stone size : 4mm Stone(s) shape : Cushion Material : Opal Stone type : Natural Color : Red-Orange Clarity : Eye-clean Mohs hardness : 5¨C6.5 Refractive index : 1.37¨C1.45 Enhancement : None (N) Specific gravity (g/cm3) : 2.15 Please Note: ? Care: Clean with warm, soapy water; never clean using steam or ultrasonics. ? Unless precisely calibrated to an exact size, gemstone sizes vary slightly. Rio allows a tolerance of +/¨C 0.1mm for gemstones 4mm and smaller. ? Mined in America, this gemstone material is sent to Germany for cutting.