Aquamarine: the blue member of the beryl family
The same mineral as emerald and morganite, coloured a soft sea blue by a trace of iron.
Aquamarine is beryl, a mineral made of beryllium, aluminium, silicon and oxygen. Pure beryl is colourless. A small amount of iron turns it blue or blue-green, and that is aquamarine. Chromium or vanadium makes green emerald, and manganese makes pink morganite. Same crystal, different trace element.
Beryl grows as six-sided prisms in granite pegmatites, coarse-grained rocks that cool slowly from the last fluids of a magma body. Some crystals grow large and clear enough to facet. Most of what is mined is cloudy, cracked or pale, and that material becomes beads, tumbled stones and chips.
The colour range runs from almost clear to sky blue to sea green. Deeper blue is rarer. Much of the cut aquamarine on the market has been gently heated to drive off the green tint and leave a cleaner blue. The change is stable and widely accepted in the gem trade.
For a shop, aquamarine covers every budget. Crushed chips and semi-polished tumbled stones are easy add-ons, bead bracelets sell as birthstone gifts, and cut gems serve jewellers and collectors. The name helps too. It comes from the Latin for "water of the sea", and customers remember it.
Iron makes it blue. Chromium makes it emerald. Manganese makes it morganite. All three are beryl.
