There's something about blue-green stones that pulls people in, and aquamarine has been doing that for centuries. The name comes from Latin — water and sea — and one look explains why. Sailors once carried it, convinced it would keep the water calm. That habit didn't survive, but the reputation did. Today, a piece of aquamarine gemstone shows up on wrists and necks for reasons beyond looks. Some wear it for astrology, others just like the color. Either way, this stone has staying power.