Chariots on Fire introduces: 

Aquamarine

In name, aquamarine is immediately-suggestive of its hue: a stunningly-transparent, light-infused blue.  In fact, its color is bequeathed from the occurrence of iron impurities within an otherwise colorless beryl crystal.  Aquamarine carries with it a purifying, protective mystique perhaps first endowed to it by sailors, who were known to have the stone sewn into the lining of their coats prior to the undertaking of any seafaring journey.  As aquamarine evokes the expansive, sublime essence of both sea and sky, the stone is said to convey a promise of the eternal.