I have not seen a lot of finished Paraiba/paraiba type gemstones, I have certainly cut a fair amount of different grades of rough. I have also kept my ear to the ground and filled the air with questions.
Since I am sure that the gemstone that was described in the last comment came from Mozambique, I will start with a little history on the quality of cuprian material that has come from Mozambique.
Many colors have come from the Mozambique deposit, but the only clean material that came out at first was a dark rather dense purple red. It came in rather larger sized pieces and could be partially heat treated to a lighter shade of lavender or completely changed to a pale blue to green color. Some of the first cuprian material I got to cut was material like this. All of it was water worn, so it was hard to see its purity and at least some of the material was sawed not cobbled. While ending up rather pale, it has a wonderful color that I had not seen in tourmaline before. I even sent my first stone back to my principle supplier in Africa to share the new color.
Along with the lavender explosion, I was getting really nicely colored rough that was generally smaller and included. I was also able to purchase some exceptional pieces of rough at this time because I was willing to pay a good price for purple/blue purple material. Now this was before copper was discovered in samples that I sent the GIA and purples like the kind copper/manganese produce in tourmaline are very rare. Still purple was not yet a commercial color in tourmaline, so the prices were still moderate compared to great Rubellite/Indicolite etc.
When copper was discovered and announced in the reverse color changers I have come to call Laurellite the prices of rough went much higher. For a variety of reasons the level of clarity significantly decreased also. I am sure that the heating of some of the rough to produce cyan material was part of the reason for the increase in flaws etc. But I have no way if telling whether a tourmaline has been heated or not. As I said earlier, having some residual purple in the gemstone does NOT guaranteed that is has not been heated.
Now what does the trade do with a significant amount of expensive and desirable material that can have its beauty enhance by a simple treatment? They have been extensively using resin materials to hide inclusions after the material has been heated. And I would say that only a small percentage of cuprian tourmaline from Mozambique comes in the desirable cyan color without heating.
So my guess is that the beautiful cyan colored tourmaline that you describe in your comment has been both heated to develop the color and treated with resin in enhance its clarity. Seeing the “rainbow” effect is a dead give away that it has had clarity enhancement. Not all cuprian tourmaline is enhanceable by heating, but greed can push people to endanger a beautiful gemstone by heating even if the gain in color maybe marginal.
Having said all that, I still can see your beautiful gemstone in my minds eye. A rare and unique beauty that I would be pleased to own.