Aquamarine
Aquamarine is beryl — the same mineral family as emerald and morganite — coloured by trace iron. Ceylon material tends toward a clear, pale sea-blue that stays bright rather than going grey.
It is a 7.5 to 8 on the Mohs scale and takes an exceptionally clean polish, so large stones with no visible inclusions are common. That makes it the most affordable way to own a big, eye-clean coloured stone.
