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 Post subject: Synthetic Tourmaline
PostPosted: Thu Dec 02, 2010 2:53 am 
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Does anyone know of any synthetic Tourmaline manufactured in the last 60 years also are there any other natural stones with the same refractive index 1.65/1.66 with the same sapphire blue colour as indicolite.
Probably not the right section but..... how (can) i do a specific gravity test without heavy liquids,ive done this with gold specimens ,can you do the same with gemstones?and what multipliers would i use?


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Thu Dec 02, 2010 9:23 am 
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Blue stones with RI +/-1.65 : apatite and euclase

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 Post subject: Re: Synthetic Tourmaline
PostPosted: Thu Dec 02, 2010 11:34 am 
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The largest synthetic tourmalines ever created have been only millimeters in size. They have NEVER been commercially available.


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Thu Dec 02, 2010 11:51 am 
lightspeed wrote:
Probably not the right section but..... how (can) i do a specific gravity test without heavy liquids,ive done this with gold specimens ,can you do the same with gemstones?and what multipliers would i use?


Hydrostatic method. Click on <The Gemology Project> in the left-hand panel of this page for 'how-to' details'.


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Thu Dec 02, 2010 7:50 pm 
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Thanks for your input all,
Noticed that apatite is very close to S.G.of tourmaline but the hardness is far from being able to confuse.Good to know that tourmaline hasnt been simulated in large sizes for jewelry use.Cant find any mention of Euclase in my gemmo book,but sounds like the Feldspar group?
Thanks once again for info and on Hydrostatic testing too =D>
Took a while but i eventually found Barbra's link to table of contents for Gemology project and found what i was looking for regarding hydrostatic testing,now i'm trying to get consistent results on the carat scale,will persist and try a few things,results dont quite add up just yet and am busy trying to eradicate variables.
Avagoodweekend
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 Post subject: Re: Synthetic Tourmaline
PostPosted: Fri Dec 03, 2010 2:57 am 
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Barbra Voltaire wrote:
The largest synthetic tourmalines ever created have been only millimeters in size. They have NEVER been commercially available.


I've never seen one but I have been told about them, apparently synthetic tourmaline is available but is many times the cost of natural and they all get blowed up.

Tourmaline is very good at measuring how much blowing up power you have.

As they are all synthetic achroite...who cares.

Tony.

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 Post subject: Re: Synthetic Tourmaline
PostPosted: Fri Dec 03, 2010 11:25 am 
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Quote:
I've never seen one but I have been told about them, apparently synthetic tourmaline is available but is many times the cost of natural and they all get blowed up.


That is 100% incorrect information.
There is NO commercially available synthetic tourmaline on any market.

Information straight from Tom Chatham.


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Fri Dec 03, 2010 5:23 pm 
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I suspect the good Dr. is referring to material custom manufactured for military/technical use in blast gauges and hence "many times the normal price" and definitely not commercial. I have a distant recollection of having seen something like this mentioned also, god knows when and where, except the story has a strong too-good-to-be-true odour, like the alligators in the sewers of New York, so as Tony suggests, it may well be apocryphal. Be interesting to find out though. Has anyone else heard similar?

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 Post subject: Re: Synthetic Tourmaline
PostPosted: Sat Dec 04, 2010 12:47 am 
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The largest examples of synthetic tourmaline ever made in any laboratory for any reason have only been millimeters in size.
There were some papers written a couple years ago inferring that much of the tourmaline available on the market was a synthetic product.
There were many people who blindly accepted this information without question. When the subject was thoroughly researched and vetted, it was determined that the assertion was completely false.


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Sun Dec 05, 2010 2:04 pm 
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Hi

In reading Michael O'Donoghues book Artificial Gemstones , he writes 'The chemical nature of the material to be grown is of great importance . I am sometimes asked why there is no synthetic tourmalines or silicate garnets . It is because both these gems minerals are compounds quite complicated chemically , with several compounds which will have different melting points . It is easy to melt a substance but cooling it at just that rate which will avoid incongruent melting and production of an unsatisfactory solid takes a great deal of prior research as well as engineering skills "


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Sun Dec 12, 2010 10:44 pm 
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I would like to offer a link to an article written by Bear Williams:
http://www.gemologyonline.com/ST.pdf
and share with you a direct quote from him:
Bear Williams wrote:
"George Rossman has the entire worlds production of synthetic tourmaline in a matchbox."


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Sun Dec 12, 2010 11:11 pm 
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dragonstek wrote:
Hi

In reading Michael O'Donoghues book Artificial Gemstones , he writes 'The chemical nature of the material to be grown is of great importance . I am sometimes asked why there is no synthetic tourmalines or silicate garnets . It is because both these gems minerals are compounds quite complicated chemically , with several compounds which will have different melting points . It is easy to melt a substance but cooling it at just that rate which will avoid incongruent melting and production of an unsatisfactory solid takes a great deal of prior research as well as engineering skills "


That's why nature doesn't make them by melting anything. Both garnets and tourmalines grow from elements which precipitate out of water based solutions. Not that this makes growing them easy, but it does point to the futility of trying to grow these crystals from a melt.

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 Post subject: Re: Synthetic Tourmaline
PostPosted: Tue Dec 14, 2010 10:55 am 
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michael_e wrote:
That's why nature doesn't make them by melting anything. Both garnets and tourmalines grow from elements which precipitate out of water based solutions. Not that this makes growing them easy, but it does point to the futility of trying to grow these crystals from a melt.



Don't most garnets form as magmatic in origin, and have a nominally anhydrous nature due to this? And yet others will continue to form through metamorphic processes?


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 Post subject: Re: Synthetic Tourmaline
PostPosted: Tue Dec 14, 2010 1:30 pm 
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Bear Williams- SGL wrote:
Don't most garnets form as magmatic in origin, and have a nominally anhydrous nature due to this? And yet others will continue to form through metamorphic processes?


If you mean "most" by volume, then I'm sure that you're correct, though I'd be curious about the actual percentage of water in the magmatic conditions that garnets are forming under. I do think that most gem quality garnets are to be found in areas where water is more prevalent, such as in pegmatites and in metamorphic conditions such as skarns.

This is interesting to me in that the mountains around here, (Cascades in Washington), have a widely varying geology and have garnet in lot of different rock types. The bulk are found widely disseminated in the metamorphic rocks surrounding a variety of plutons. The plutons themselves don't seem to have as much garnet visible, but when you do find it in large enough sizes to see, it can be very nicely displayed as small vibrant bands and clusters.

As for tourmalines, don't they all form naturally in hydrothermal solutions and in association with quartz?

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 Post subject: Re: Synthetic Tourmaline
PostPosted: Tue Dec 14, 2010 11:27 pm 
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Hello Barbra,

I would like to offer my sincere apologies for my comments. Using hearsay to dispute with a professional was a bit dim on my part. Apparently the term synthetic has a different meaning to those outside of the gem industry.

It turns out that the "synthetic tourmaline" used in blast sensors is made from powdered NATURAL Tourmaline mixed with a ceramic material.

Tony.

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