Found in Australia and considered to be the most valuable and rarest opal of all, black opal appears dark from afar, but as you draw closer its ethereal fire can be seen. Our London jeweler hand-sets this precious stone into gleaming British sterling silver and adds cubic zirconia to create a pair of earrings that is truly one-of-a-kind. Handcrafted exclusively for Uno Alla Volta, from the heart and hands of the artisan. Dimensions - Approximately 0.75 inches long, posts.