How the Size of an Aquamarine Affects its Value
Aquamarine gemstones, even of very good quality, are very affordable when under 1 carat. A gemstone this small will never command a high price (under $100).
Very fine gemstones that are over 3 carats or so will start to see a price jump because of their size. Very large stones of 10 carats or more will be again, exponentially more expensive. Aquamarine gemstones of this size are not impossible to find, but they are not nearly as prevalent as blue topaz, for example.
Size increases the value of an aquamarine only after color and clarity. If you have the choice between a 4 carat aquamarine with intense blue color and a 10 carat aquamarine with a pale color, most likely the 4 carat gemstone will be more valuable.
However, a 10 carat aquamarine with equally intense color can cost 5 times more than the 4 carat stone.