How to tell if an opal is real??? Real opal vs lab created has always been a hot topic of the gemstone world. So, let’s dive in and see how you can spot a synthetic opal. A lab-created or fake opal does not radiate brightly under UV light! Unlike real opal, the opal created in the lab let out peculiar, arranged color flashes. These opals are oddly absorbent when compared to natural opals.