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 Post subject: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 1:50 pm 
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Dear All ,

i have bought one pinkish purple tourmaline long time ago in Mozambique . There was an inclusion that i have sliced to leave the stone loup clean . Then i faceted what i have sliced and went to GIT certificate and appear to have copper content .

I sent the stone back to Bangkok with few more tourmalines a week ago . I would like to show you 3 spectrum of 2 tourmalines ( 1 blue spectrum and 1 yellow spectrum is for the same stone ,, and 2nd blue spectrum is for another tourmaline ) .

I would like to have your opinions . I trust a lot on experts of this forum.

question : Are my both tourmalines copper and manganese bearing tourmaline ???

Thank you and Regards .


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 3:39 pm 
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The answer to this question is much more complicated than it would at first appear, or that most people, including many Gemologists understand it to be.

The proof of copper is a peak at around 900nm showing copper, and also the prescence of Manganese peaks betwen 415nm - 530nm. Since the resolution of your charts doesn't have marking around this number we must estimate. But it does look like it has peaks in the proper areas. However it may also have peaks in the higher areas (700+nm) indicating Iron which would disqualify it. These determinations are made using a UV-Vis-NIR spectrometer that I am used to making the call from, and which we dont have a chert for. I hate to make calls from spectrums that are calibrated and draw differently than mine.

However, the stadardized definition for Gemmological Labs also have a requirement for color. I have attached a copy of this agreed upon critera for labs. You will note that Purple/Pink are not included. So, in their present color they should not get a report of Paraiba from one of the major labs like GIA which are party to the standardized nomenclature agreement. GIA will put a coment like this on their reports regarding this situation.

"Although this stone does contain copper and manganese, the properties are not consistent with what is called “paraiba tourmaline” in the trade. "

This may be seen as even more confusing since many (possibly even most) Paraiba Blue/Geen (Windex colored) Pariba Tourmaline are Purple and Pink prior to heat treating. So will not be classified by labs as Paraiba until heat treated. Which is undetectable by the labs to boot.

So, in the end it looks likely that your stones with the 900nm peaks have potential to be Paaraiba, the pink/purple one currently is not. The blue may be.

I hope you find this information interesting and helpful.

Steve


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ParaibaTypeRequirements.pdf [100.49 KiB]
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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 5:40 pm 
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Dear Steve ,

i want to thank you . This is my problem . I do have lot of exeptionnals rough tourmalines ( many of them are cuprian and only gem quality , loup clean raw materials i kept since 20 years ago ).

When i went to Bangkok 2016 , i took with me 2 princess . One was dichroic , neon blue electrique / green color . I faceted it and that time i join that wonderful forum and posted that stone , come out a 21,36 carats , no blow , no respect for dimensions , proportions and angles , thai cut ( with all my respect ) . In thailand , cutters only think how to get more weight at the finish .

I plan to send it soonly that bluish green cuprian tourmaline from Mozambique to Mr Bruce Fry for a re cut if he still can do it for me as we agreed long time ago .

I will show you my pinkish purple , it is a 79 carats loup clean and a lot of few cuprian ( 5 g up , 3g up 2g up , smallest is 1,02 g .

And 2 well known laboratory in Bangkok told me that ALL MY STONES DO NOT HAVE COPPER , and i remember that i read in OUR FORUM , that copper in tourmalines shows 2 pics , most important one is around 900 nm .

Something wrong happen in Bangkok in most small to medium gem lab internationally wellknown .
I will post report with stone attached from gemlab , pictures and videos .
I thanks GOD that i bring all my stuff back to me .


Thank you .


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 6:25 pm 
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Dear Steve ,

i want to thank you . This is my problem . I do have lot of exeptionnals rough tourmalines ( many of them are cuprian and only gem quality , loup clean raw materials i kept since 20 years ago ). My pink/purple does have copper and manganese . The small orangy pink 1,79 carats i faceted from the 79 carats does have copper as reffered by GIT certificate . Here is the stone attached on gemlab reports . Two spectrum that showed a huge pic around 900nm , i posted , are from the 79 carats test pink/purple . See attached files please .

When i went to Bangkok 2016 , i took with me 2 princess . One was dichroic , neon blue electrique / green color . I faceted it and that time i join that wonderful forum and posted that stone , come out a 21,36 carats , no blow , no respect for dimensions , proportions and angles , thai cut ( with all my respect ) . In thailand , cutters only think how to get more weight at the finish .

I plan to send it soonly that bluish green cuprian tourmaline from Mozambique to Mr Bruce Fry for a re cut if he still can do it for me as we agreed long time ago .

I will show you my pinkish purple , it is a 79 carats loup clean and a lot of few cuprian ( 5 g up , 3g up 2g up , smallest is 1,02 g .

And 2 well known laboratory in Bangkok told me that ALL MY STONES DO NOT HAVE COPPER , and i remember that i read in OUR FORUM , that copper in tourmalines shows 2 pics , most important one is around 900 nm .

Something wrong happen in Bangkok in most small to medium gem lab internationally wellknown .
I will post report with stone attached from gemlab , pictures and videos .
I thanks GOD that i bring all my stuff back to me .


Thank you .


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 7:01 pm 
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Here more infos .

Thank you .


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 10:54 pm 
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Hello ,

more infos about this post .


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File comment: 21,36 cts , the one Mr Bruce Fry will recut for me
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File comment: 21,36 cts
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File comment: 14,25 cts greenish yellow ( more greenish than yellowish)
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File comment: 79 carats pinkish/purple in gemlab 2
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File comment: 79 carats pinkish/purple spectrum done in gemlab 1
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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Fri Mar 31, 2023 11:19 pm 
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These are few pictures of the others neon electric natural blue tourmaline i had sent also with the lot . Most show our nice pic around 900 nm .

I think i should buy a spectrometer . Or maybe a spectrophotometer . Any advice ? I would like a good quality ( 100 nm to 1100 nm ) . And whats the difference between them in reality ?

Few pictures of the rough under white light .


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File comment: 5g up
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File comment: approx 2 g
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File comment: approx 2 g
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File comment: 27,6 cts bluish green
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File comment: 1g up
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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Sat Apr 01, 2023 6:30 pm 
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Is there a specific question on a specific stone you would like help with?

Where do you live?


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Sat Apr 01, 2023 10:19 pm 
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The general specific question has already been clarified by your confirmation of the presence of copper in my stones, given VERY SIGNIFICANT peaks around 900 nm. Now I know that several of my tourmalines from Mozambique are copper and manganese bearing tourmalines, I will no longer sell them raw but rather have them cut and enhanced (by heating those that must be), certified and sold. I think I will buy a spectrophotometer and learn to read the spectra of the different types of stones that interest me. Always this famous question of knowing what percentage of copper is required to define that a stone can be heated and have the famous electric neon blue so much sought after.

Of course your opinion interests me to know if the pinkish purple tourmaline can be heated and if we can have an electric neon blue. The ideal is to take the risk with the 1.79 carat orangy pink sliced from this stone, heat it and see. Or should I do a basic quantitative analysis to determine the exact content of copper and manganese to know if we have the "minimum" required to be able to heat it?
All blues ones , i will leave them naturals . I will plan to cut them later .

And questions, I will always have because we never stop learning. Especially since I have not done any studies or any gemological training. Love at first sight in Mozambique in 2003 with the wonderful colors of tourmalines that passed under my nose, because I was staying with a relative who was in this fabulous universe of precious stones specialized only in tourmalines . I spent many years in Nampula.

Regarding where I live, I will send you a private message.

Regards .


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Sun Apr 02, 2023 11:42 pm 
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Hello again,

I think the question of what is cuprian tourmaline or paraiba tourmaline is even more complicated than the discusion has presented. The following points come from my investigation of many gems that showed copper absorption. They come in a very wide range of colors.

1, You do NOT need manganese in the cuprian tourmaline to be paraiba. I have had my 14 carat Mozambique paraiba type gem tested and it has only a single digit (ppm) level of manganese in the gem. It never needed to be heated and yet has the classic blue color.

2, The original definition of paraiba does consider a required tone level (same as the origiiinal location), related to Brazilian material, of appropriate colors when discussing paraiba. I have a couple carat SRB that I called an achroite. I had purchased the rough as a sample of a blue purple tourmaline, but I could not see the color under different lights in the finished gem. My kids could see it and I finally could with difficulty. Yet it produced a beautiful copper curve with my spectrometer. I do not think it is a paraiba, heated or not.

3, The only color, not dominated by blue, I have found that is certifed as paraiba is grass green. I have a 5 carat bright grass green SRB that the GIA just certified as paraiba tourmaline.

4. I am of the opinion, after decades of searching and now years of chercking with my spectrometer, that the combination of titanium, iron and manganese can deplicate all the cuprian paraiba colors except vivid, saturated purples. Greens are particularly hard to separate into iron based or copper based gems, since it is common for them to have the same color. (I have not given up the quest.)

5, The cuprian reverse Alexandrite color changer from Mozambique, that I have come to call Laurellite is in the purple blue to blue green range was Not certified by the GIA as paraiba. (It goes from bluish in incandescent light to purplish in natural light.)

6, They heated everything that came out of the original find in the state of Paraiba, The material in the pink to red range was greatly reduced in beauty after heating.

7, There is more in the rich world of cupian tourmaline and I am actively working to get research done on this fascinating subject.

Bruce


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 Post subject: Re: spectrum of 2 tourmalines
PostPosted: Mon Apr 03, 2023 11:30 am 
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nasco wrote:
Of course your opinion interests me to know if the pinkish purple tourmaline can be heated and if we can have an electric neon blue. The ideal is to take the risk with the 1.79 carat orangy pink sliced from this stone, heat it and see. Or should I do a basic quantitative analysis to determine the exact content of copper and manganese to know if we have the "minimum" required to be able to heat it?


When the opportunity is available due to trimming it is standard practice to take a slice of tourmaline off a peice of rough to use as a heating test stone to find the minimum temp that produces a good color. The risks when heating Tourmaline is high, so less heat equals less risk.


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