Opal triplet and sterling silver 925. Size stone: 1,5 cm x 3.1 cm / Diameter: 18,5 mm Weight: 8,9 gram An opal triplet is a partially fabricated gemstone made of three layers: a thin slice of opal, a dark backing, and a clear, domed quartz. The "triplet" name refers to these three layers, not to the number of colors in the opal itself. This composite stone is designed to look like a solid black opal at a lower cost by magnifying the opal's color and protecting it with the cap. Shipping registered.