gems, tourmaline, Paraíba tourmaline, Brazil, cuprian tourmaline, Mozambique, Nigeria

The most paraiba type tourmaline in the market recently is colored by copper only. This time some blue - green tourmalines were requested to check if they are paraiba or not. And they are colored by both iron and copper. We still don't have the conclusive criteria, but in this article we explain their features and why it is not so simple to set the criteria.