A moonstone is a milky-white gemstone that seems to glow from within, like captured moonlight. When you tilt a moonstone in the light, you see a silvery or bluish shimmer that appears to float just beneath its surface, an effect called adularescence. This mysterious glow happens because the stone contains microscopic layers that reflect light in special ways.

Moonstones have fascinated people for thousands of years. Ancient Romans believed they were formed from frozen moonbeams. In India, moonstones were considered sacred and thought to bring good fortune. Today, jewelers prize them for rings, necklaces, and earrings.

The stone is actually a type of feldspar, one of the most common minerals on Earth, but moonstones with strong adularescence are relatively rare. The finest specimens come from Sri Lanka, though they’re also found in India, Australia, and Madagascar.

When you hold a good moonstone, you can understand why ancient people thought it was magical: the way light moves through it really does look like you’re holding a piece of moonlight in your hand.