The blue of sea water
Aquamarine is blue beryl, coloured by iron. Large, clean crystals are found more often than in most species, so size is less of a constraint and colour decides almost everything.
The deepest blues set the price; the name Santa Maria, from a Brazilian mine, is still used in the trade for the most intense colour. Brazil, Mozambique, Nigeria, Madagascar and Pakistan produce. Much aquamarine is heated to remove a green tint.
SOURCE
Brazil, Mozambique
Also Nigeria, Madagascar and Pakistan.
VALUE DRIVER
Depth of blue
Pale stones are common; saturated blue is not.
TREATMENT
Often heated
Heating removes green; untreated fine blue is scarcer.