Aquamarine comes in three basic varieties I am aware of: A "pure" aqua shade, a "greenish" aqua shade and a rare "deep greenish" aqua shade. This is very much a color for which rarity is relative, and somewhat regional. For example, aquamarine can be quite rare on the US East Coast, but somewhat more common locally, on certain parts of the US West coast. Deep aquamarine pieces are sometimes confused with turquoise, but the two are quite different.