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 Post subject: green tourmaline - how do i know i'm getting the real thing
PostPosted: Sun Aug 06, 2006 12:34 pm 
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How difficult is it to distinguish green tourmaline from any other green transparent stone, assuming the stone is mounted in a ring with metal on all sides (so I don't think specific gravity can be measured)? If the ring were taken to a graduate gemologist, could he/she identify it with 99% certainty?


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 Post subject:
PostPosted: Sun Aug 06, 2006 12:48 pm 
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A G.G. certainly should be able to identify a tourmaline for you as there are a number of tests that can be performed on the stone to identify it even though it is mounted.

With tourmaline - RI, birefringence, pleochroism, double refraction, inclusions, and sometimes spectra can all be identifing tests.


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 Post subject:
PostPosted: Mon Aug 07, 2006 10:43 am 
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What about the difference between topaz and tourmaline? I read that topaz can come in green (I was not aware of this) but they are both double refractive and have RIs that overlap.


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 Post subject:
PostPosted: Mon Aug 07, 2006 11:04 am 
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The chance of having a green topaz that isn't coated is pretty slim. Coatings are easily identified.

Optic figure and birefringence will separate a topaz from a tourmaline.


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 Post subject:
PostPosted: Wed Aug 16, 2006 12:28 am 
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a properly adjusted heat probe on a presidium duo tester and then compared next to similar test stones that are proven topaz and tourmaline will separate the two easily.. dave


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 Post subject:
PostPosted: Wed Aug 16, 2006 1:05 am 
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Specific gravity is a great way to seperate as well.


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 Post subject:
PostPosted: Tue Nov 14, 2006 10:27 am 
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Snizzy wrote:
The chance of having a green topaz that isn't coated is pretty slim. Coatings are easily identified.

Optic figure and birefringence will separate a topaz from a tourmaline.


I have a green topaz that isn't coated. It is diffused.

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 Post subject:
PostPosted: Thu Sep 27, 2007 7:18 pm 
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Diffused? With what?

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 Post subject:
PostPosted: Mon Nov 16, 2009 9:54 am 
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Greetings from Namibia!
Over here, in the bush, we like things simple and sure.
I think the most simple way to find out if the stone you have is tourmaline or not is to rub it with some soft material, like a piece of cloth and see if the stone attracts any fine ash (try to burn some news paper). Do not let the stone touch the ash, hold it a little bit over the ash and you will start to see very fine particles flying towards the rubbed stone surface. If you have hair on your head, you can try rubbing the stone over them. I use a piece of springbok hide (a type of antelope). If it doesn't work the first time, rub harder, the friction creates electricity in the stone.
If after that the ash is not attracted to the stone, you've got yourself something else. Not a tourmaline.
Hope that helped...although, given the date of the original post, i doubt it. :)


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 Post subject:
PostPosted: Mon Nov 16, 2009 11:27 am 
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Excellent advice Andy and completely accurate!

We've discussed this "diffusion" claim with topaz before on the forum.
Can anyone recall where?


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 Post subject:
PostPosted: Tue Nov 17, 2009 3:03 pm 
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Barbra, thank you! I wish all the other gems had easily recognizable features, like tourmaline. That would make life a little bit more simple =) Maybe you know of other unique properties to a particular gem. Some tricks that can be used in the field, and with guaranteed results. Like for example, rubbing gold speciment over unglazed porcelain. If the line is black/dark brown, then it's not gold. That can be an interesting forum topic for the beginners. Something like, "Easy and 100% gem identification, without fancy equipment".


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 Post subject:
PostPosted: Tue Nov 17, 2009 3:06 pm 
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Andy_Namibia wrote:
Barbra, thank you! I wish all the other gems had easily recognizable features, like tourmaline. That would make life a little bit more simple =) Maybe you know of other unique properties to a particular gem. Some tricks that can be used in the field, and with guaranteed results. Like for example, rubbing gold speciment over unglazed porcelain. If the line is black/dark brown, then it's not gold. That can be an interesting forum topic for the beginners. Something like, "Easy and 100% gem identification, without fancy equipment".


Just don't mention the Chelsea filter. :D

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 Post subject:
PostPosted: Tue Nov 17, 2009 3:37 pm 
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Jason wrote:
Just don't mention the Chelsea filter. :D


:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

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 Post subject:
PostPosted: Tue Nov 17, 2009 5:06 pm 
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you can use a chels....oh..woops :lol: :lol: :lol: :lol: :lol: :lol:

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 Post subject:
PostPosted: Wed Nov 18, 2009 2:33 am 
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Chelsea filter...neat! Gotta get me one of those.


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