How can you tell if a stone is a tourmaline?

[Arkteia]

I shall be able to tell for sure in several days. But as I am typing this post, have nothing but a loupe on me. The stone looks like a tourmaline, at least I can not imagine what else it could be - it is pink and was mined in Russia.

I can not get to my office because of the weather. The stone is not very old, let's assume 20 years old. It could be dichroic, I do see two lines, but I can not look straight through one facet because of the cut. I know that tourmaine is piezoelectric but how do I check i? Rub it against a woolen sweater and see if it attracts small pieces of paper, like I would do with amber? Is there any other way?

I am just curious how much you can do without anything but a loupe on you.

 

[Pandora II]

By dichroic, it means that the stone will show two different colours through a dichroscope. Only doubly refractive, or 'anisotropic' stones CAN be dichroic, but not all anisotropic stones ARE. The birefringence or amount of double refraction of tourmaline is too small to see with just a loupe, but it's possible that you might see dichroism.

In the case of a pink tourmaline it would show a deeper and paler pink colour. Sometimes with pink tourmalines a cutter will want to emphasize the colour and so will cut the stone with the table perpendicular to the c-axis along which the colour is darker (the opposite is true with green tourmaline). So you might see a darker shade through the table than you will through the side of the stone if it has been cut this way. More often they are cut with a mix of C-axis and A/B axis showing through the table in which case you probably can't tell with just a loupe.

Inclusion-wise you might see needles or fluid-filled inclusions.

The FGA teaches a lot of loupe-only IDing but much of the time you can only get so far before you need to resort to other instruments, especially with cut stones.

Other possibilities could be pink corundum, pink topaz, pink beryl (morganite) or even kunzite.

 

[Arkteia]

Thank you, Pandora. I would cross out morganite because it is too pale and my stone is saturated and darker. I can't wait to get some formal appraisal; I can do something myself but not yet much.

 

[LD]

Crasru - don't rule out Morganite just yet because it comes in every variation between pale pink, pale peach, right the way to very strongly saturated pink and the same again for peach. It actually has a wider colour range than Kunzite which tends to only follow the pink spectrum. Russia is a large producer of hydrothermal quartz so that may be another possibility.

 

[LD]

I don't know if you're familiar with these people but knowing you're Russian, I thought you might like to browse this website! Somewhere in the e-library it also gives a list of which gems are mined specifically in Russian - that might help to narrow down your search.

http://www.minsoc.ru

 

[chrono]

I don’t think you can look for dichroism with the naked eye that well after it is cut. A dichroscope will tell you for sure though. Unfortunately, there’s no way to tell conclusively if it is a tourmaline armed only with a loupe.