Is there any different in the raman spectrum of synthetic and real sapphire? Or can we notice any different with FTIR or UV-VIS-NIR spectroscopy? I have attached 2 raman spectra of sapphire and shell. Would appreciate if any of you can give me some comments. Thanks!
i'm not able to see your pics, i'm the only one? ciao alberto
No. I can't either. But it seems that several others have viewed them. This occasionally seems to happen. Don't know why but wonder about the method of attachment??
Thanks for your reply. I found that the spectrum for synthetic and real sapphire are very identical. In your opinion, what is the best way to identify them using spectroscopic method?
Joined: Fri May 12, 2006 11:24 am Posts: 7523 Location: Rome, Italy
zen wrote:
In your opinion, what is the best way to identify them using spectroscopic method?
I can't be of much help on this side cos i don't own a raman spectrometer, hopefully i could have an usable UV-VIS-NIR setup in this lifetime. However i really don't need BIG guns to solve the synth/nat sapphire issue, brain-microscope-books is the trio i always used and still feel very confortable with them ciao alberto
Thanks for your reply. I found that the spectrum for synthetic and real sapphire are very identical. In your opinion, what is the best way to identify them using spectroscopic method?
THanks!
OK, I'm lost....Can we have a little more information here?
1. You present two graphs. One is labelled 'Shell' and the other 'Sapphire'. Does Shell = Synthetic? Or??
2. In each graph, both the intensity of the collected return from the target and the wavenumber (related mathematically to the wavelength of the collected light) are plainly and widely different. In what ways do you see them to be similar?
3. AIUI, Raman spectroscopy is about observing molecular vibration under coherent light bombardment. Since the chemical composition a synthetic and a natural Sapphire is essentially the same, why should you expect Raman spectroscopy to differentiate reliably between the two?
I am sorry that I have appeared not very clear to myself too and causing the confusion. I just got too carried away and was asking multiple questions without explaining more.
1) The first graph is synthetic sapphire and the second one is indeed shell. I did not put the spectrum for the real sapphire. 2) as above 3) I am wondering if those inclusion or impurities might cause some little peaks that can be distinct for us to differentiate any difference? If not do you know of a better way?
I am sorry that I have appeared not very clear to myself too and causing the confusion....
Hi Zen,
It's OK, All of us do it from time to time
Quote:
1) The first graph is synthetic sapphire and the second one is indeed shell. I did not put the spectrum for the real sapphire. 2) as above 3) I am wondering if those inclusion or impurities might cause some little peaks that can be distinct for us to differentiate any difference? If not do you know of a better way?
If you use the link Alberto gave you, you will see that your basic idea is correct. Synthetic Sapphire (and Ruby) is commonly is fairly pure and lacks the random selection of impurities that Mother Earth adds to natural gemstones. But you don't need Raman to detect this. Synthetics are made quickly and natural gemstone rather slowly, with the result that there are different microscopic flaws which give visual clues as to whether the stone is natural or synthetic. This is a skilled business, requiring much learning and practice; for some; it becomes a life-time study. A synthesiser can add trace elements to his stuff easily enough but forging in days what took nature thousands of years to make and perhaps alter, break and mend again (as one example) is not really practical. Also, there are often microscopic flaws in the synthetic material that are a give-away for synthetic production.
Forgive me if this makes it seem easy to tell natural from synthetic; it isn't - but it can be done and, it seems, Raman spectroscopy is simply not the best tool for tackling this work. The more flawless a natural gemstone is the more valuable it is - and the closer the chemical composition of the natural and the doctored synthetic can become.
Not sure that's the answer you want to hear but it's the best I can do for you....
Thanks so much for your prompt reply. I really appeciate so much. It been very nice to learn so much from you guys in this forum. I am new in the industry with some materials characterization background. I know the difficulties involve in the identification real/synthetic gemstones, but wish to really try using some kind of spectoscopic methods to characterizate these minerals. Is there any possibibility? Thanks.
Thanks so much for your prompt reply. I really appeciate so much. It been very nice to learn so much from you guys in this forum. I am new in the industry with some materials characterization background. I know the difficulties involve in the identification real/synthetic gemstones, but wish to really try using some kind of spectoscopic methods to characterizate these minerals. Is there any possibibility? Thanks.
Regards, Zen
Dear Zen.
I hope that you will stay with this forum, not only to read what others put here but to make some contributions of your own. We are all learners, just at differennt stages along that learning road and the thoughts of others with similar interests are rarely without value - even if one does not always agree with them
It would be very convenient if one form or another of spectroscopy could differentiate with a high degree of certainty between synthetic and natural Corundum - and also between treated and untreated natural Corundum. Certainly, there are more than a few who actively research such a possibility.
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