O&G Australia genuine Opal doublet pendant set in 14K Yellow Gold. Opal gemstone measures 7x10mm. Opal gemstone has midnight blue and neon green coloring. Pendant measures 11x21mm including bail. Bail fits up to 3mm. Opal, a precious gemstone, was called the Queen of Gems by the ancient Romans because it included the colors of all other gems. Opal is prized for its unique play of color, the ability to diffract light into flashes of rainbow color. Opal is the October birthstone.