I saw this post on pinetrist about rare "double blue" aquamarines. I've never heard this term before. What does it mean?
Never heard of the term either - its probably not an official term but rather made up by the dealer to describe a deeper blue color and not just a light colored aquamarine.
Term used for Mozambican Aquamarine,to emphase the intense blue, that at the eye sight check at the sun, the color remain unfazed otherwise denoted as Santa Maria too!