Or a cheaper used unit from Stephen (4k US vs. 12K Euro).
Seriously, Raman spectrometers are the best gem identifiers a gemologist is likely to have. If you want to go low cost, a refractometer (not a reflectometer) is pretty good, especially when augmented with a polariscope, gem microscope, dichroscope, and specific gravity tester. (If you want MORE expensive, adding an FTIR (fourier transform infrared spectrometer) is good too - then XRF and XRD, etc...
Stephens Raman machines are excellent. We worked on a project to get spectrums of the entire GIA A & B charts, plus the complete set from the latest GIA Lab Manual installed on the machines. This means that there are currently just over 500 stone spectrums on the machines. The Machines have a matching algorithm built in. I find that if I get a good scan of a stone, I get a positive match for between 85% and 90% of the time. This is pretty much a fast, "point and shoot" identification in these cases.
If no match is found the machine hooks up wirelessly to my laptop to transfer the scanned spectrum for analysis with David's custom written application. This allows me to clean up the scan, and limit the range of the spectrum to make it a better candidate for analysis. The software has the RRUFF and U of A spectrum databases in it. I can then run David's matching program against the scanned data. This produces a match for the majority of of samples. If not, it orders the database in order of the closest match. I can then do as you say and do a manual compare. Between all of these process I almost always end up with a good identification, without a frustratingly long search through the whole RRUFF database.
Hehehe. I like the sound of StephoRaman but that would be taking way too much credit for myself. I would love to find a supply of affordable FTIR or UV-Vis-NIR spectrometers, and if I ever do we'll try something similar for sure. As-is, I do have an FTIR spectrometer and an FTIR microscope, but we haven't figured out how to handle either one (mostly for lack of trying, each will likely be a long project and we haven't gotten to them). Even the supply of affordable Ahuras seems to have dried up--the relative glut seems to have been related to them being end-of-lifed by fisher scientific, meaning some universities upgraded to the next model. (As a side-note, we have actually tried the newer model, and while it is a bit smaller it doesn't produce better spectra--performance seems identical.)
Joined: Fri Nov 01, 2013 9:16 am Posts: 239 Location: Germany
1bwana1 wrote:
Stephens Raman machines are excellent. We worked on a project to get spectrums of the entire GIA A & B charts, plus the complete set from the latest GIA Lab Manual installed on the machines. This means that there are currently just over 500 stone spectrums on the machines. The Machines have a matching algorithm built in. I find that if I get a good scan of a stone, I get a positive match for between 85% and 90% of the time. This is pretty much a fast, "point and shoot" identification in these cases.
If no match is found the machine hooks up wirelessly to my laptop to transfer the scanned spectrum for analysis with David's custom written application. This allows me to clean up the scan, and limit the range of the spectrum to make it a better candidate for analysis. The software has the RRUFF and U of A spectrum databases in it. I can then run David's matching program against the scanned data. This produces a match for the majority of of samples. If not, it orders the database in order of the closest match. I can then do as you say and do a manual compare. Between all of these process I almost always end up with a good identification, without a frustratingly long search through the whole RRUFF database.
and one very big point no body is mentioning, it is portable For us a device for all day use and helped us a lot up to now.
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