Moonstone Crystal Eyeglass / Sunglass Necklace. Dark navy faceted crystals and gold plated accents are mere visual appetizers for the deliciousness the Moonstone crystals offer on this beautiful glasses chain. The Moonstone crystals have an opal look as they refract the light around them through opaque subtle colors. This eyeglass necklace measures 28 inches long with adjustable stretch ends to fit most frames.