Unpolished opal
Photograph by John Cancalosi, Alamy

Opal is October's Birthstone

Opals form over millions of years where hot, mineral-rich ooze seeps into rock cracks. Tiny spheres of silica stack up and harden to become opals. The way light bounces off the silica creates an opal's colorful shimmer.

Old-School Myths

Wearing an opal will make you invisible—according to an old legend. An opal was also believed to bring beauty, success, and happiness, as well as medicinal powers. It was once said that an opal could even protect a person from lightning!

More to explore!

Rocks and minerals