Aquamarine, the birthstone for March, is also the alternative gift for the sixteenth and traditional gift of the eighteenth wedding anniversaries. Aquamarine is named for its color (Latin for "water of the sea"). It would be clear Beryl (aluminum beryllium silicate) without traces of Iron introduced into the crystal lattice structure.
Gem quality aquamarine grows in pegmatites, where crystals can be very large and very pure. Aquamarine is readily available in very large sizes, but is less practical for jewelry use in the larger sizes so prices per carat tend to decrease over 25 carats. Smaller sizes are rarely saturated in color enough to be attractive; however, some African material is known for its intense color in the stones under 5 carats and can sell for more per carat than larger stones of the same quality.
Nearly all blue is heat treated to remove the brown-yellow color component. Aquamarine's most valuable color is the moderately strong, medium-dark blue to slightly greenish blue.