Lapis Lazuli
This deep blue stone includes tiny flecks of mica, like a night sky full of stars. It's most well-known source is deep in the mountains of modern Afghanistan.
From antiquity, lapis lazuli has been worn in the belief that it will ward off evil. In ancient Egypt, it was powdered and worn about the eyes to improve eyesight. Today, it is considered by some to be an aid to balancing the brow chakra (which influences vision and hearing). Imbalances of the brow (or blue) chakra are said to cause headaches, anxiety and disorders of the skin.