Aquamarine is light blue, blue-green and dark blue. The highest quality is transparent and is a gemstone-quality transparent variety of beryl closely related to the emerald. Aquamarine often pales if left out in the sun. Since the Dark Ages people thought that it could magically overcome the effects of poison. Sailors traveled with the crystals, believing that it would ensure a safe voyage, and guarantee a safe return. They also believed the mermaid's lower body was made of aquamarine.