How can you tell if an opal is genuine?

To determine if an opal is genuine, examine its play-of-color, which is a vibrant, shifting spectrum of colors that should appear throughout the stone. Authentic opals often have a unique internal structure that creates this effect, while synthetic or imitation stones may lack depth or show a more uniform appearance. Additionally, check for natural inclusions or imperfections, as genuine opals typically have some. Finally, consider having the stone appraised by a certified gemologist for an expert evaluation.