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 Post subject: A B C Jade and their ftir / Uv vis spectra
PostPosted: Tue Nov 24, 2009 1:56 pm 
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Hi all,

Two questions. First, can the assumption be made that resin free jade, determined using ftir, is by definition dye free?

Second, is the 690nm peak in green jade exclusive to undyed material?


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PostPosted: Tue Nov 24, 2009 3:24 pm 
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Hello Yorick,

Would have to say that I have seen polymer treated jade that has not been dyed.... and dyed jade could just as easily be not treated with resins.

With regards the 691nm peak, while this is indicative of the Cr3 that would reside in natural greens, it does not exclude the piece from also having been dyed. This I've also seen in some of the jade bangles... one area was natural, while the other section was dyed.

Both FTIR and spectrometers need to be used in these cases, both with an eye to thoroughness.

Bear


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PostPosted: Tue Nov 24, 2009 3:47 pm 
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Hi Bear,

Was sort of expecting you to reply and am very gratefull you did. I have a large lot of jade that needs sorting out. Also have a UVVIS and FTIR bench to my disposal. Now, the FTIR resin detection seems to be a piece of cake, not to worried about this. My main problem is getting reliable data for the comparison of the 600 - 700nm range VIS spectras of dyed and undyed jade. My observations so far are that the undyed pieces show three bands, 630, 660 and 690 (approx). The stones of which I know that they are C or B/C seem to give me one band in this range, sometimes with a 690 band. Is the lack of the three peaks conclusive? I read about a band from 630 to 670nm in dyed pieces, but am yet to see one.

You dont happend to have some sample spectras that you could send (sorry about the cheeckyness).


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PostPosted: Tue Nov 24, 2009 4:13 pm 
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Hope I remember how to use the image shack.

Image

This is what you should expect to see in general when comparing the dyed to natural greens in vis spectrometers. The typical 690nm for the natural where it does not exist in dyed, and the broader absorption centered ~670nm in the dyed, but not present in nat.

Another thing to watch out for is: Is the item actually jadeite!? Often you will also see a 437nm line that is indicative of where the Fe is present in jadeite and is used as diagnostic by many.

bw


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PostPosted: Tue Nov 24, 2009 4:17 pm 
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Bear, you ROCK! No pun intended.


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PostPosted: Sat Nov 28, 2009 9:16 am 
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Hey Yorick,

My copy of the latest Gems and Jewellery has just arrived and there is a summary in there from an article in the journal which covers this question.

The Journal article is available online to members of the Gem-A. Don't know if you have access to it?

If not PM me :wink:


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PostPosted: Sat Nov 28, 2009 11:35 am 
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Frank wrote:
Hey Yorick,

My copy of the latest Gems and Jewellery has just arrived and there is a summary in there from an article in the journal which covers this question.

The Journal article is available online to members of the Gem-A. Don't know if you have access to it?

If not PM me :wink:


Frank,
Would this mean you are going to render access to those who are not members, or perhaps forward the copy of Gem-A material? Should everyone then, apply for this service?
Bear


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PostPosted: Sat Nov 28, 2009 4:54 pm 
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Ah no Bear. Wouldn't that be a breach of copyright? I might write up a summary of pertinent points or send copies of any graphs. This would of course be done in the spirit of education. I would actually advise anyone who can afford it to subscribe to some of the gemmology journals. But I appreciate that many can't afford it and I'd be willing to share any knowledge I learn from these publications with anyone who is interested :P


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PostPosted: Sat Nov 28, 2009 5:33 pm 
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Hi Frank,

For the sake of education, and my expired gem a
membership (Bowing my head in shame!), the pertinent points would be much appreciated. I have a whole bunch of the G&G's with some info but all help on this one would beuch appreciated. Let's say that I will promise , cross my heart, to renew my subscription.


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PostPosted: Thu Dec 17, 2009 9:25 am 
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Just as a point of interest here are some transmission IR's I did years ago for Mark Liccini.
It was so long ago I cannot even remember the context.

Image

Image

Sadly, my Fisher Dual Spectranal died a long time ago. A cat puked in its electronics while it was running. She liked to sit on the warm IR source.

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PostPosted: Thu Dec 17, 2009 12:16 pm 
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Quote:
A cat puked in its electronics while it was running


:smt105


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PostPosted: Thu Dec 17, 2009 12:43 pm 
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I admit it sounds funny now, but at the time it was a tragedy. I really relied on that instrument for my polymer and other consulting work. It was a valuable tool then- Obsolete now, anyway, what with FTIR. So is the cat. She died ages ago.

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PostPosted: Thu Dec 17, 2009 9:46 pm 
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sorry, gearloose, but, i'm with tim on this one! cannot believe the cat vomited in the electronics and ruined the equipment, which ain't cheap.


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PostPosted: Thu Dec 17, 2009 10:01 pm 
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Quote:
cannot believe the cat vomited in the electronics and ruined the equipment, which ain't cheap.


Believe it. You know how they are with warmth. The IR Glow source had a vented housing. A perfect cat warmer. Near it, inside, were PC Boards filled with discrete components for the servo amplifiers and the TC amplifier.

While IR is rarely used for minerals, with proper sample prepration (Or with an ATiR Crystal) it could be of possible value. Mark L. had a find of what he thought was a new jade source, and it was just getting interesting. The IR was bult in the '70's and was not worth fixing, even though it had a new $400 detector. This is not like the UV/Vis units commonly used. It runs hot near the source.
Somewhere around here I have a Sadler's index for IR analysis of minerals, so someone has done it before...

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 Post subject: Re: A B C Jade and their ftir / Uv vis spectra
PostPosted: Thu Mar 22, 2012 7:43 am 
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hi folks,

resuscitate this old thread just to ask if someone would be as kind to post a couple of FT-IR spectras of untreated and dyed jade.
thank you in advance for helping me on this. :D

ciao
alberto

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