Pearls are the only gemstones made by living creatures. Mollusks produce pearls by depositing layers of calcium carbonate around microscopic irritants that get lodged in their shells, usually not a grain of sand, as commonly believed.
A relatively modern gemstone, alexandrite was discovered in Russian emerald mines located in the Ural Mountains. Legends claim that it was discovered in 1834 on the same day that future Russian Czar Alexander II came of age, hence the name honoring him.
June’s third birthstone, moonstone, was named by the Roman natural historian Pliny, who wrote that moonstone’s shimmery appearance shifted with the phases of the moon.