Post subject: Re: I have $500 to spend on gem id equipment
Posted: Mon Nov 05, 2018 6:12 am
Gemology Online Veteran
Joined: Thu Mar 19, 2015 9:55 am Posts: 543
Horses for courses, both have their strengths and weaknesses, but from a comparison of both of mine, the Beck is a professional grade instrument, whilst the OPL is amateur quality.
Post subject: Re: I have $500 to spend on gem id equipment
Posted: Tue Nov 06, 2018 5:53 am
Gemology Online Veteran
Joined: Thu Mar 19, 2015 9:55 am Posts: 543
My opinion, for what it is worth, is that the Raman is just another whizzy woo instrument that raises as many questions as it answers. It must be nearly 100 years since Basil Anderson first had the idea of using a spectroscope in gem i.d., and gemmologists are still arguing about spectra. I expect the same will apply to the Raman. Professional is the ability of the gemmologist to interpret the results given.
Post subject: Re: I have $500 to spend on gem id equipment
Posted: Tue Nov 06, 2018 11:07 am
Gold Member
Joined: Thu May 12, 2016 2:18 am Posts: 1542
Pretty impressive "Whizzy Woo" instrument though. This from an article in the most recent edition of AGTA's PRISM Magazine.
"Raman spectroscopy is the only technique which can provide for a fast, reliable and non destructive identi- fication of polished and rough gems, either loose or mounted, without the need of further test (Figure 1 left). It is not by chance that a Raman spectrum is often called “fingerprint”. Every single material has its own and, if the spectrum is clearly readable and not noisy, its 100% accurate"
Bartender, I'll have another glass of that Whizzy Woo please.....
My opinion, for what it is worth, is that the Raman is just another whizzy woo instrument that raises as many questions as it answers.
Not to be too contrary, but it really doesn't. It may be whizzy woo, but it usually doesn't raise questions because it's pretty purpose-specific: it gives you a nice, accurate fingerprint of the material you're looking at which generally allows clean identification of the base material. It very rarely gives you more information than that--as Bwana mentioned it's almost never going to tell you about chromophores or treatments (aside from a few exceptions, like cuprian tourmaline absorbing NIR so strongly it throws a scanning error on our 780nm raman spectrometer [this does need more testing], or hiddenite having an extra chromium peak, or synthetic spinel having broader peaks). So generally speaking it answers one question but does it very well, and because of that (aside from maybe some extreme minutia) there isn't much to argue about. With the RRUFF database freely available it's not hard to match a spectrum against every mineral there is. Of course there are limitations as there are with any piece of equipment--I didn't throw out my refractometer or forget how to take an SG when I got a raman. On the other hand, I haven't broken out the refractometer too many times since either, and I really don't miss the smell of the fluid.
Alan F. wrote:
Professional is the ability of the gemmologist to interpret the results given.
This is true. You need to be able to correctly interpret the results and know the limitations of the equipment and the data it produces, and even then the hard work of determining treatment and/or synthetic status is still ahead of you.
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