Aquamarine is a type of beryl, which makes it a close cousin of the emerald. Unlike emeralds, though, aquamarines are relatively common and typically clearer than emeralds, with fewer inclusions or cracks. Like other silicates, aquamarine is mostly made up of silicon and oxygen, and the finest of these hexagonal blue crystals are formed via slow-cooling igneous rocks known as pegmatites. Some natural aquamarine crystals are more than a...Continue Reading