Aquamarine is part of the Beryl crystal family, which includes Emerald and the lovely pink Morganite; Aquamarine is less costly than Emerald, being considerably more abundant, but is more costly than most semi-precious gemstones, and gradually becoming still more costly due to ever-increasing world-wide demand, especially when its clarity and colour is the equal of the Aquamarine in these earstuds shown above.
Aquamarine is considerably more expensive than the gemstone most similar in colour, namely Blue Topaz.