A single opal has many moods—or at least seems to—which is exactly what makes each one so irresistible. The gems flicker from brilliant intensity to demure understatement (and back again) with the barest motion, and display colors from deep sea blue to searing red and every hue in between. That changeability has made them a source of wonder wherever they’ve surfaced. Ancient Greeks thought opals bestowed the power of prophecy and a Bedouin legend insisted that the gems came from the heavens with lightning strikes. Their mystical associations make opals a natural fit for jewelry with an otherworldly air, like the crescent moon ring from EF Collection or Celine Daoust’s starry gold pendant. And the remarkable color and dramatic fire of fine opals mean that they’re the ideal focus for streamlined jewels, like Irene Neuwirth’s halo ring or Liesel Love Jewelry’s sleek cuff. However they’re worn, opals have a habit of changing their owners’ mood for the better.