Most people will remember that Prince Harry gave Meghan Markle an Aquamarine ring from his mother Princess Diana. Some have estimated that her ring weighs about 30 carats. Definitely very big. We have a couple of big-enough aquamarine rings, in "Maldive-Blue". Sorry we coined that term ourselves. It really fits the blue we last saw of the sea at the Maldives.
Aquamarines belong to this group of gemstones known as Beryl. It's the same group of gemtsones as Emeralds, has a MOH's hardness of 7.5 - 8.0.
From GIA's website:
" Aquamarine is pastel blue, greenish blue, or green-blue. The preferred aquamarine color is a dark blue to slightly greenish blue with moderate intensity and is most striking in gems of over 5-cts. Fine stones show even blue color with no zoning "
So it has to be big enough, blue enough to be attractive.
Some aquamarines are too light, see-through.
The better ones have a big fire in them. Shiny.
It's very unique blue, and you should have some aquamarines in your collection.