I was asked a while back if I had any indicolite in a specific shape and size. The specification of “indicolite” gave me pause, because what is an indicolite anyway?
Well, it turns out that indicolite just used as a term for the blue varieties of tourmaline, and is also known by the term “indigolite”. I am not a chemist, gemologist or a physicist, as I have reiterated before, so I had never given it any real meaningful thought.
Tourmaline is mostly classified by color, and color is usually an indication of mineral presence. Indicolite is usually but it’s complicated by the fact that paraiba and cuprian tourmalines are colored by copper, while other darker blue tourmalines are colored by iron.
So it seems as though classification of a tourmaline is more of a continuum rather than a linear grouping.
I typically don’t really delve too far into these things because I look at the stone as a piece of art and a medium I have to work with rather than it’s chemical composition. When I do get questions like this, I ask people who are more knowledgeable than I am (a huge thanks to all of you who do their best to explain these things to me!) so I can answer to the best of my ability, or just point them to somewhere else that might have the answers they are looking for.
Now, ask about color, shape and proportion, and then you’ll get a long monologue!