Blue Opal History, Meaning, Symbolism, Healing Properties & More Blue opal gemstone is one of the many varieties of opal stone that is available in shades of blue-green and blue. Sometimes, the term “blue opal” also describes the opaque varieties of opal found in Machu Pichu, which generally possesses a teal color. Unlike other gemstones, blue opal is not a mineral – rather, it is classified as a mineraloid.