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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 10:20 am 
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That is the squiggly line problem I referred to above. Much much worse with FTIR , Raman and PL techniques, as well as all the other, alphabet soup techniques.

And most gemologists are not also trained as analytical chemists or physicists. Letting computer software tell you what the "answer" is is professionally very risky business.
And that is the thin ice one steps on with advanced techniques.

The standards GIA established are trade standards not scientific standards.


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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 10:26 am 
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..............

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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 10:30 am 
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You know.....I'm going to contact The director of the Certicication Center at Moscow University and ask for an explanation of this unit and find out about the database they use and how it was amassed.

I suspect it was compiled by graduate students in their gemology program, but I'll see.

Also, I remember him mentioning the necessity of the development of software that anyone can utilize without holding a PhD.


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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 10:31 am 
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Barbra Voltaire wrote:
Also, I remember him mentioning the necessity of the development of software that anyone can utilize without holding a PhD.


yep, exactly what you (and i) said......

ciao
albé

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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 10:52 am 
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I only know of two examples of such software up to now.

One is Marty Haske's SAS 2000 system which knows what its measurement parameters are and takes a Diamond only and tells you what its color grade is. It also automatically warns you of things such as radiation damage and a few other spectral features which it was laboriously programmed to look for.

The other is the programming contained in the Gran Colorimeter which works amazingly well when it does work. Most of the examples don't seem to work well.

No one who writes anything like this will give it away inexpensively.

There is currently tons of database search software for FTIR and Raman for use in the drug industries. They use these instruments for QC starting with incoming material and ending with shooting through packaging and capsules for outgoing. You shoot your spectrum and the software searches the database(s) you have bought and paid for
and returns a bunch of potential matches. When they know the potential adulterants present in particular raw materials and contaminants that they might add in their own processes this can be quite useful. But when the software rings the bell an analytical chemist still gets called to figure out what the squigglies mean.

I cannot imagine it being financially feasible for the people that write this sort of thing
to ever make any money doing it for gemology. This is a variant of the dream of the magic box that you put a stone in it and it tells you what it is. The people who really can utilize these techniques are both analytical chemists and gemologists.


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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 11:00 am 
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I was quite amazed with the sophistication of the computerized laser scanning tomography of rough diamonds done at the Alrosa Headquarters in Moscow. The unit, not only locates inclusions but calculates the options for the best final product.

This technology was also employed at other certification centers to determine diamond clarity in cut stones and produce plots WITH CLARITY GRADES, repeatedly, accurately and most importantly without human subjectivity.

The scanning unit could be used and understood by ALL employees, although, certainly the development of the software was crazy complicated and useful to a very small demographic.


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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 12:23 pm 
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G4Lab wrote:
I only know of two examples of such software up to now.

One is Marty Haske's SAS 2000 system which knows what its measurement parameters are and takes a Diamond only and tells you what its color grade is. It also automatically warns you of things such as radiation damage and a few other spectral features which it was laboriously programmed to look for.

The other is the programming contained in the Gran Colorimeter which works amazingly well when it does work. Most of the examples don't seem to work well.
.


Thanks Gene.. Let me start with the fact that no one wants to give away man years of work, and receive nothing in return.

Labs (INCLUDING GIA) consider their work proprietary, and even go so far as to actively censor what is published in their 501c3 journals, supposedly to make sure the PhDs that develop treatments don't know as much as they do (even though much is already in the scientific literature). Example: Has anyone EVER seen criterion published on what distinguishes a natural versus an irradiated green diamond?

Purchasers of scientific equipment utilize that equipment to give them an edge in purchasing rough or cut stones, most especially diamonds, and they guard their independent research like the crown jewels.. it is their life blood.

As to Gene's comment about blind diamond colorimeters.. If the stone is fluorescent or non cape series, you can't trust the result, for multiple technical reasons.

2 or 3 color grades off can put a big dent in your bottom line, and even one color grade can be make or break. Start with our "blessed" yardsticks (GIA master stones). Are they 30 or are they 42 inches long, and I'm not kidding when I say that.

As to Raman versus photoluminescent effects to identify stones or their treatments, it appears to me that the photoluminescent effects have the most bearing in the gemmological world, especially after the proliferation of HPHT treatment in diamonds. Many spectra for pure identifiction are available online today. The RUFF project and Geoge Rossman's spectroscopy server are two classic examples. The effect of treatments are a different matter.

An example of the photoluminescent utility is explicit when GIA actively (and still does) withheld the fact from the trade that type IIa diamonds (usually) have natural radiation damage, the 741nm signature destroyed by HPHT, which can be re-introduced and modified by annealing to mimic the original signature. Back in 2006 Debeers published a new HPHT criteria regarding the half-height half-width with respect to original color in IIa diamonds, but other than the fact that you might need very high resolution and EXPENSIVE spectrocopy to make this call, ignore other data that implies that one might be able to anneal and narrow the induced radiation photoluminescent effects to below the published criteria for natural. One wonders what happened to the 20 years stockpile of brown IIa industrial rough that DeBeers said they had about year 2000, or if true value of the stockpile was known before they went private. But that is a political $$ question.

Cheap spectrometers may be a boon for the gemological world, if they work properly, which we have shown that some don't, noteably due to detectors not coated to reduce/eliminate the Etalon effect. That simplistically, results in a signal indicated at one wavelength being effected by a source intensity at a far removed wavelength. Simple devision DOESN'T WORK correctly (to get true transmittance), when you stick a stone in the beam whose attenuation at the far removed wavelength is different than that at the wavelength of interest.

Think of it as trying to extract "a" from the equation
T = (aX +bY)/(X+Y) when you don't know "b"

Single measurement techniques such as used by Raman/photoluminescent techniques have the inherent low frequency signal imbedded, and are of limited use, especially for any sort of database, but may be qualitatively usefull if one knows what they are dealing with.

Also, Gene mentioned the use of a narrow Rugate notch filter to eliminate the laser wavelength in a Raman/photoluminescent signal. The anti-Stokes signal (below the excitation wavelength) is much smaller than the Stokes signal (that above the excitation wavelength) so that for most gemological applications a much cheaper long pass filter will suffice, in my opinion.

Foreign sources may be way ahead of the curve, dollar wise, but who cares about any potential intellectual property rights anyway. Reverse engineer it.

Just my two cents.

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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 12:31 pm 
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Barbra Voltaire wrote:
I was quite amazed with the sophistication of the computerized laser scanning tomography of rough diamonds done at the Alrosa Headquarters in Moscow. The unit, not only locates inclusions but calculates the options for the best final product.

This technology was also employed at other certification centers to determine diamond clarity in cut stones and produce plots WITH CLARITY GRADES, repeatedly, accurately and most importantly without human subjectivity.

The scanning unit could be used and understood by ALL employees, although, certainly the development of the software was crazy complicated and useful to a very small demographic.


The question to be asked would be what is the limit that it can be reliably used. SI or VS?

I really really sort of doubt VVS.

Size of the inclusion used to be a criteria, but location, location, location and more subjectivity has crept into the US grading process, some of which I agree with, some not.

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 Post subject: Re: Spectrometer
PostPosted: Fri Aug 26, 2011 4:37 pm 
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Apparently one of the "edges" one gets by having the little Bruker FTIR
is the ability to sort which diamonds are good candidates for HPHT treatments.
If one is a diamond broker or someone else who has a good stream of goods going through ones establishment, the unit might pay for itself fairly quickly by picking out those stones.
Or so the story goes from the East Coast Bruker FTIR sales rep.

I don't think people are buying them to test Jade.

Measuring diamond clarity is something which could utilize technologies fairly well established in other uses and the trade standards would be fairly easy to model. Nonetheless, I would point out the GIA at their labs still use gemologists and not machines to clarity grade diamonds. It would be much cheaper to do so with instrumentation which never needs a potty break nor gets the flu nor asks for a raise. I think if it could be done reliably by machine vision they would be doing it that way. The GIA labs bring in many tens of millions of dollars a year in lab fees. They could afford the development project.


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 Post subject: Re: Spectrometer
PostPosted: Mon Jan 14, 2013 2:40 pm 
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Enhanced Spectroscopy has now set up their distribution in the USA. This is the company that built the Raman unit which Barbra saw on her recent trip to Russia. It was developed in conjunction with Russian gemological institutes including Dr. Shelementiev.

Their system is very scalable, and the basic system can be added to in steps, without losing earlier investments.
These start at $10,000 for a basic 532 nm Raman/PL unit, and go up to around $30,000 for a unit mounted on an Olympus microscope.They will fabricate mounts for other microscopes. They have three interchangeable lasers at 405 , 532, and 730 nm and the lasers can be changed easily without optical realignment. They have a large gemological database that comes with it, and their software can directly accept files from the RRUFF public database.

They are very interested in the gemology business, and their prices seem feasible.
http://www.enspectr.com/en/index.htm

They have videos on their site which demonstrate their instruments being used for gemology.

Also HRD is now selling the Bruker Alpha FTIR for use in testing diamonds.
Here is their propaganda which in itself is somewhat informative.
http://www.lancering.be/email/hrdantwer ... EN_WEB.pdf
I don't know how much HRD is selling this for but here in the USA you can buy a Bruker Alpha for in the neighborhood of $20,000 plus some extra for the OPUS software and a DRIFT (Diffuse Reflectance ) sampling accessory. Bruker USA is in Billerica Massachussetts.


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 Post subject: Re: Spectrometer
PostPosted: Thu Jan 31, 2013 4:39 pm 
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http://www.stellarnet-inc.com/PopularCo ... ystems.htm

StellarNet (who used to collaborate with Ocean Optics) have released a bunch of low priced Raman instrumentation starting at $4,000


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 Post subject: Re: Spectrometer
PostPosted: Thu Jan 31, 2013 5:43 pm 
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Thanks for the heads up, Gene :D

Quote:
Raman instrumentation starting at $4,000


I browsed the link and found the basic spectometer alone costs $3500

So what would be the price for a complete system, including spectrometer, laser, probe, PL capabilities, sample stage & holders, gemological oriented software & reference libraries, calibration standards, and safety systems?

I'd say 10-12k is more fair estimate for getting basic pieces for starting do it yourself project from zero. Add 700-900 hours of your spare time, a pinch of knowledge & couple of costly mistakes and you're done :-)

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 Post subject: Re: Spectrometer
PostPosted: Thu Jan 31, 2013 6:39 pm 
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The Raman probe is $4,000 The laser is $5,300 . Though you could probably get either for considerably less, with some shopping. The probe might be built by Kaiser Optical. It is makes for a quite flexible system which could be used at several wavelengths and would be easy to probe mounted jewelry with.
http://www.kosi.com/Raman_Spectroscopy/ ... php?ss=300

I have had some very good experiences with StellarNet in sharp contrast to the numerous experiences I and others have had with Ocean Optics.

Their software is also free and can read library spectra. They have an excellent customer support team.
Such a system could have 4/cm resolution, and they have a TE cooled spectrometer for a small amount extra which would extend the sensitivity. They use a 2000 pixel spectrometer which also has a better S/N than 4,000 pixel units. (1000 pixel units from 15 years ago have even better perfomance which is something none of these companies want to talk about)


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