Opals get their color from butterfly wings.

False. Though the legends surrounding opals are some of the most in fascinating gemstone lore, the fairytale Kimberley West’s grandfather told was just that: A fairytale.

Opals form when water seeps through sandstone. As the water travels into the earth, it picks up silicon dioxide from the sandstone. The water collects in natural fissures in the rock and, when it evaporates, leaves behind the silicon dioxide. Over time, pressure from above hardens the silicon into opal.

Unlike diamonds, emeralds, sapphires and rubies, opals are not made of crystals. Instead, silica balls surrounded by leftover water (opals are about 6 percent water) are sort of smooshed together – yeah, I know “smoosh” isn’t a technical term, but you get the idea.

The silica balls act like prisms, reflecting light and giving that lovely play of color that makes opals so desirable.

While the geological process that creates opals doesn’t involve butterfly wings, it can involve dinosaurs.

Seriously. Scientists in Australia found a dinosaur whose bones had partially turned to opal. Check out this great YouTube video showing “Erik,” the dinosaur made of opals.

Meet Erik the Opal Dinosaur