June has two birthstones: Pearl and Alexandrite
Historically, pearls have been used as an adornment for centuries. They were one of the favorite gem materials of the Roman Empire; later in Tudor England, the 1500s were known as the pearl age. Pearls are unique as they are the only gems from living sea creatures and require no faceting or polishing to reveal their natural beauty. In the early 1900s, the first successful commercial culturing of round saltwater pearls began. Since the 1920s, cultured pearls have almost completely replaced natural pearls in the market.
A relatively modern gem, Alexandrite, was first discovered in Russia in 1831 during the reign of its namesake, Czar Alexander II, and is an extremely rare chrysoberyl with chameleon-like qualities. Its color is a lovely green in both daylight and fluorescent light; it changes color to a purplish red in incandescent light. Due to its rarity, some jewelers stock synthetic versions of this enchanting gemstone. (Synthetic gemstones are man-made alternatives to the natural material, possessing the same physical, optical, and chemical properties as the natural gemstone.)
Source: American Gem Society