When you see a metallic-like shimmer of blues and greens on or near the surface of a gem, you can refer to it as labradorescence. It is only seen in a few varieties of gems and the word comes from Labradorite; a gem which demonstrates the very best example of this wonderful visual effect.
This phenomenon is a type of iridescence caused by repeated, microscopically thin layers at the surface of the gemstone. The finest pieces have very striking looks, which skilled Lapidarists take care to orient to the best advantage when faceting the gemstone. Other gemstones where you will see labradorescence include other members of the Feldspar family such as Moonstone.
Labradorescence is an incredibly captivating visual effect, and one of the real treasures gifted from Mother Nature.
