The document discusses the three June birthstones: pearl, alexandrite, and moonstone. Pearls have a hardness of 2.5-4.5 on the Mohs scale while alexandrite is one of the harder gemstones at 8.5. Moonstones have a hardness of 6.0. Alexandrite is rare and changes color from green to red in different lighting. Moonstone is named for its sheen caused by light diffraction through feldspar layers and is found in various colors. It was believed by Romans to come from solidified moon rays.