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PostPosted: Sun Jan 11, 2009 5:08 pm 
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Sorry...I'm thinking of some of the data I've seen misinterpreted using a Raman Spectroscopic microscope without sufficient background in data analysis.


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PostPosted: Sun Jan 11, 2009 6:26 pm 
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Oh, raman is a whole nother can of worms.. You'll be looking at an emerald and think it was laid by a mammal because someone forgot to wipe the fingerprint oils off of it!

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PostPosted: Sun Jan 11, 2009 7:20 pm 
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ghehehe, indeed John...

Barbra, I too see a great advantage in starting a thread that discusses the different advanced testing methods. I even hope for members of this board to be able to share their findings and start a databank with data collected from known samples.
The fact that the average gemologist hasn't had any training in this field doesn't seem to be a valid point not to help them to learn about it. A chapter on 'laboratory testing' or 'advanced testing' could open doors and prove to be a nice learning centre for all of us. In the beginning it'll be a discussion bringing forth a lot of links to 'how and what' and probably will generate more questions then answers but after a (short) while I'm sure the collected intellect of this group can start contributing to the science. We already have a few members that have access to spectrometers, and those numbers will rise in the not to far future. A free and open database of samples is something that would be very handy to everybody. Why not here?

spectrum graph of the day
subtitle; known samples only


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PostPosted: Sun Jan 11, 2009 10:06 pm 
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Tim wrote:
The fact that the average gemologist hasn't had any training in this field doesn't seem to be a valid point not to help them to learn about it.

Of course that is true, but who here would moderate such a thread to ensure accuracy?

I doubt any "gemologist" who simply graduated from GIA, DGemG or Gem-A is qualified to make sure that the information presented is accurate.

Certainly none of us wish to use this platform to propagate concepts that may be totally or partially inaccurate, misleading or misunderstood.

Therefore, such a thread would need to be moderated by someone who had specialized training in the gemological application of various sophisticated spectrographic instruments, to ensure that we are not going off on some blind leading the blind tangent.

Volunteers?
Brian?


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PostPosted: Mon Jan 12, 2009 3:56 pm 
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Barbra wrote:
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Of course that is true, but who here would moderate such a thread to ensure accuracy?


I see what you mean but if we would apply this to everything a lot of posts shouldn't pass moderating. Inclusion interpretation for instance is a very wobbly subject, but we all see the advantage of it. We dive into the unknown so many times here...

I would hate to see a great learning opportunity to be thrown out the window here just because of recent memories of a certain somebody that likes to show us how it's not done... Maybe he will learn a thing or two as well from it and will stop stating silly stuff... :wink:


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PostPosted: Mon Jan 12, 2009 5:17 pm 
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Fine, start the thread...we'll see where it goes.


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PostPosted: Mon Jan 12, 2009 6:07 pm 
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For most gemologists I agree with Dr. Bill. But I am seeing from personal experience that there are folks that want more than a view through a spectroscope. And like Jleb says the hand spec is the basic exercise.

I would say for the forseeable future anyone reading this should forget about taking your own Raman and/or FTIR spectra. They are advanced techniques and you really need to know how to beat up on a piece of advanced equipment. I have an FTIR spectrometer that I got free and I haven't even hooked it up. It is taped up with duct tape and a big cannister of strong dessicant inside. It has optics (IR optics) made of potassium bromide which is just like table salt. One exposure to humidity and the instrument can go into the dumpster. It needs a constant purge of what is called zero air. Dewpoint around minus 100. It actually came with a gadget that does that but I have to set up a compressor and a refrigerated drier I ran across to go with it. It will want one or two liters per minute of clean dried air for the rest of my life. Thats alot of electricity to the compressor and pre dryer. And that is only one aspect. Every detail has its devil.

There are setups that have handheld probes and supposedly easy to use data acquisition schemes. Sometimes these are to be set up by the more trained person so that repetitive measurements can be performed by less trained folks, as in QC situations. They just aren't plug and play. But neither of these two methods will be popularly priced in the near future.

Right now to get into an Ocean optics spectrometer you can start at about $1100. But that is for the spectrometer only and a version that has 650 (ie. a hobbled loss leader) pixels for the visible range. The software is another $200. That is a spectrometer with an SMA 905 fiber optic input. You haven't bought a fiber nor a light source yet. nor an integrating sphere nor something to hold your gem accurately in the way of the light.

You could do a Hanneman video spectroscope for alot less if you wanted to and might even be able to turn it into the wavy line of the spectrum if you ran across the right software. But to do that you need some kind of video frame grabber. Ux4 has experimented a lot with these methods too.

This does not mean that those who have elected to travel this path should not continue and share the info. As Dr. Bill says they are advanced gemophiles and researchers. Seriously pursuing this equipment practically qualifies you. There are a lot of things that need to be learned about and get comfortable with in UV VIS NIR absortion spectroscopy, first. Until you have a decent comfort level with that you will have your heart broken by the more advanced techniques and their cranky and difficult to use equipment.


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PostPosted: Mon Jan 12, 2009 9:04 pm 
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All the ghetto spectroscopy we want to do has already been done by the home astronomy fanatics. There is free software and tons of info on how to collect and interpret stellar spectrums already done by these people. It looks pretty simple to adapt this to a gemology based system. Google away.. we can post data and links in a new thread.

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PostPosted: Mon Jan 12, 2009 9:19 pm 
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Inclusion interpretation for instance is a very wobbly subject, but we all see the advantage of it. We dive into the unknown so many times here...


Yes, we do, because we know there are members of our forum with the expertise to correct misinformation and recognize misidentifications. That is why it is beneficial.
And furthermore, the reason analysis of inclusions is of paramount interest is because EVERY gemologist or hobbiest has access to a magnifying instrument.

8) But who knows, perhaps "spectrum of the day" will inspire everyone to save up for their own bench model laser ablation sampling system. It could come in handy for all sorts of things.


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PostPosted: Mon Jan 12, 2009 10:01 pm 
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But who knows, perhaps "spectrum of the day" will inspire everyone to save up for their own bench model laser ablation sampling system


judging by the pm's and mails I'm getting about microscope set-ups that may even be the case... who knows :D


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PostPosted: Tue Jan 13, 2009 1:43 am 
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W00T! What a lot of very interesting comments. So many, I don't even know where to start!

I thought the basic holdup on acceptance would be the price point. I never even considered the lack of comparison spectra. I collect these spectra with the same lack of comparison, and worse yet, post them publicly. But one can develop one's own comparisons. For example, it was really neat to see zircon sand produce the same absorption line as zircon rough, especially since the jade debacle (see below) I was none too convinced that it was zircon sand.

Also I forget that, as Gene says,
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there are a lot of things that need to be learned about and get comfortable with in UV VIS NIR absortion spectroscopy
Fortunately, I have a new crop of lab students this semester who will surely remind me of this fact. MoDo, I'm sure they would appreciate a "Spectometers for Dummies" book.

In my mind, the use of the digital spectrometer for gemologists is the same as the use of the spectroscope... pattern recognition. After all, a spectrum is just a pattern. The benefit of the digital spectrum is that it doesn't require highly-developed visual acuity and that it is (mostly**) independent of the light source used.

Most other spectroscopic methods, such as FTIR, Raman, LIBS, and NMR, are used primarily as pattern recognition. For example, the interesting case of using FTIR to identify polymer impregnated jadeite. When I was bugging my analytic chemist to use their new FTIR on a jade (which *ahem* turned out to be nephrite), the first thing he asked me "why do you want this region? ... structure here arises from hydrocarbons, which shouldn't be present in a mineral." Well duh! Hydrocarbons, the building blocks of polymers. Just pattern-recognition... if you suspect hydrocarbons, look for peaks in this particular range of the FTIR.

I have to agree, though, it is going to be some time before these spectroscopies find their way outside analytic labs. By the way, my chemist's FTIR was new, because the lab roof developed a leak right above his old FTIR. Open 'er up, all the optics had disappeared, replaced by puddles of saltwater.

And oh, as for me putting together a reference, y'all overestimate my access to material. Just ask jleb about my ruby rough! As another example, I collected a spectrum from a single piece of emerald rough that would make a pretty poor gem. Whereas I bet Jean-Marie has collected spectra from a dozen gem emeralds. (Jean-Marie, if you are reading, still waiting to see the spectrum of Vanadium Emerald).

I can see the day is approaching when we'll see even more UV-VIS-NIR spectra in the Research section (time to get busy Alberto ;)). And I'm happy to pay close attention to that. But I'm not keen on reviewing other methods. Experimental science isn't really moderated, it is more like "I got this result"... "oh yeah, well let me try it and see if I get something similar". We spend a lot of time going "did you check this?... how did you account for that?... why did you do it that way?... "

Getting back to my original question...
Quote:
...When will the spectroscope be replaced by the digital spectrometer as a commonplace tool in the repertoire of gemology?

... from the discussion, it seems gemologists and gem schools can wait several years and see how things stand then.



**of course, if a light source can't provide a certain range of wavelengths, then the best spectrometer in the world isn't going to observe anything in that range.


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PostPosted: Tue Jan 13, 2009 4:08 pm 
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As I said previously, the amateur astronomy folks have been doing spectral analysis for years and have this down..

take a look

http://www.fornax.myby.co.uk/spectroscopy.html

I am narrowing the field down on the appropriate camera/software for this application. The rather cool thing is that they have software already compensating for the RGB color filter matrix and a whole lot of other goodies for free

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PostPosted: Tue Jan 13, 2009 5:45 pm 
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The astronomy amateurs have done things that border on the miraculous.
They typically spread the spectrum much wider than we do and measure in angstrom units (10 angstroms = one nanometer)

They are now measuring the red shifts that take place because of the Doppler effect of the expanding universe.

There is a Website google Christian Buil
There is an Amateur Spectroscopy webring for astronomrs.
They sometimes use hight res digital SLRs and they also us webcams.
And extract every last bit of information that is contained in the signals.

And while we may have some headaches making light go through a gemstone only through the gemstone and nothing but the gemstone,
trying to pipe faint starlight into a spectrometer is a whole nother can of worms.

I have sold some gear to astro types and they are great fanatics. I love em. :D


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PostPosted: Tue Jan 13, 2009 6:15 pm 
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I don't know about the rest of you desktop Gemologists, but I've got a growing list of what a Gemologist is supposed to be.

Geologist
Mineralogist
Crystallographer
Forensic Lab Technician
Astronomer
Inventor
Physics and Chem. major

Definitely an underpaid profession.

If I had known this, I would have skipped the 6 month Gemology course and headed straight to the University.

Of course, I would need 30 or 40 years refunded as well. :D


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PostPosted: Wed Jan 14, 2009 9:17 am 
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Whadaya do with a dead chemist??

Barium!


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