O&G Genuine Opal Doublet (2.10cts) Pendant set in 14K Yellow Gold (0.31gms).  Opal gemstone measures 6x15mm, irregular-shape.  Pendant in total measures 6x21 with bail.  Bail fits up to 2mm.  Opal gemstone has Midnight Blue and Neon Green coloring. 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.