Gemlab Research & Technology (GLR&T) conducts independent research in gemmology and mineralogy related areas.
GLR&T is part of Gemlab Group and a subsidiary of the Canadian Institute of Gemmology (C.I.G.); Gemlab Books and Instruments offers gemmological books, gem identification equipment and products developed by GLR&T.
Early projects included colour gem grading with spectrometers and gem identification techniques using an immersion-scope. More recently portable fibre-optics spectrometers and LED light sources have expanded traditional gem testing procedures; they will become important tools for the practising gemmologist in the future. The Canadian Institute of Gemmology is in the forefront of providing professional development courses to its graduate students and members of the jewellery trade; innovative delivery methods are being studied and incorporated.
Over the years cost for electronic equipment has dropped considerably and UV-VIS-NIR and Raman spectrometers with software are now available to experienced gemmologists using a note-book computer.
GL GEM RAMAN DEVELOPMENTS
The GL Gem RamanTM is an advanced gem testing instrument for gemmologists, gem dealers, mineral collectors and others; it is also an excellent educational tool.
The GL Gem Raman software allows real-time spectral acquisition; it can be used to operate both the GL Gem Spectrometer and the GL Gem Raman making them a powerful combo unit for advanced gemstone and mineral identification. It can replace other advanced spectrometer types such as NIR256-2.5 near-infrared spectrometers, FTIR (Fourier transform spectroscopy) spectrometers and temperature regulated Raman units.
The spectra can be saved and imported into a searchable database program with over 2,500 references; the database is linked to the large on-line mineralogical RRUFF database for Raman spectra. GL Gem Raman users will also have access to the C.I.G. (Canadian Institute of Gemmology) gem reference library which is being compiled from the large C.I.G. gem study collection. Other reference databases can be consulted on-line.
The GL Gem Raman is available NOW
The GL Gem Raman is an ideal addition to the GL Gem Spectrometer which has over 100 users world-wide. The operation of the Raman unit is easy to learn. The calibration procedure in case the unit has been transported and/or exposed to shock must be conducted with safety goggles. The purchase price includes the GLGemRaman software; for educational purposes an interface is provided to search a database of over 3,000 references compiled and linked to the on-line RRUFF database.
A 2 1/2 hour workshop (GEM 370 offered by the Canadian Institute of Gemmology and other industry groups in the future) is recommended for gemmologists, mineral collectors and other users; we also provide assistance via Skype video-conferencing.
Testing procedures can be done without safety goggles; however, the user will assume complete liability as to any consequences if the unit is not operated in compliance with instructions provided.
The export of a Raman spectrometer to certain countries may require an official safety certificate. Sales to EU countries as an OEM product is possible as the end user is responsible for safety issues; contact us for further information
The GL Gem Raman is available now for a package price of under $ 8,000 FOB Vancouver, Canada .
The GL Gem Raman is a powerful testing tool for gemmologists, mineralogists, jewellery appraisers and collectors.
Here a few comments about the advantages (and disadvantages) of a Raman over other advanced gem testing instruments such as FTIR, UV-VIS-NIR spectrometer, etc:
We have chosen a 300 mW 532nm laser as excitation source as commercial units are now available at economical prices. These devices use diode lasers to “pump” a Nd-YAG laser which operates at 1064 nm. The light in this laser is frequency-doubled to give green 532 nm light output. This wavelength is about optimum for both Raman efficiency and the detector operating range. The Raman spectral range is from 200 – 2,500 cm-1 and output under 300 mW is usually sufficient and safe for the sample.
Raman spectroscopy is scattering-based, not transmission/reflection; i.e. no need for sample preparation. Only a small sample area is required; there are no movable optical parts and maintenance is minimal.
The Raman can quickly tell the difference between diamond, cubic zirconia and zircon, distinguish jadeite from nephrite, separate real from faux pearls, tell whether it is ivory or plastic; it works great on beads, carvings and gem materials set in jewellery. There is great potential for detecting treatments and colour enhancements in gemstones; it will help in the determination of the nature of diamonds, gemstones and minerals.
The GL Gem Raman has a sample compartment big enough to accomodate larger specimen and single pieces of jewellery.
A arge reference database and software is available on-line at the RRUFF Project; GL R&T together with GL Gem Raman users will build a reference database for the 532nm excitation laser used in the instrument.
GL Gem Spectrometer
|For work with larger samples and gems set in jewellery we recommend the GL Xenon Flashlight setup (see image) and/or the GL Fiber Probe with diffuser which can be purchased separately.|
Using a fiber probe with the GL Gem Spectrometer requires a customized setup with external lighting and will change several parameters for obtaining a spectrum.
Results may vary dependent on light source and its position, sample size (affecting path length) and orientation, etc.; spectra will look different from those found in the database and/or obtained with the GL 10W Halogen Gem Holder.
Please visit the special GL Gem Spectrometer page with more infos and downloadable materials.
Over the last 3 years we have tested several spectrometers and numerous soft-ware packages. The high price of commercial systems excluded many gemmologists from owning and operating such a valuable tool.
With the help of a local engineer we custom designed a broad band gem spectrometer which is affordable and highly sensitive. It uses a back illuminated CCD sensor; the software compensates for etalation in the near IR. Our diffraction grating efficiency is optimized for 500 nm (see specifications below); at 300nm it is 35%, around 1000 nm it is 45% (with averaged efficiency for both polarizations around 55%). That is better than other units costing twice as much.
Also important is a proper light source though the GL Gem SpectrometerTM can be used with a fiber probe alone; spectroscopists often develop their own setup depending on the material and the type of measurement. For gemstone analysis a tungsten halogen light source, a xenon light, various types of lasers and UV-LEDs are being used. The GL Halogen 10W is a basic light source with built-in cosine corrector, cooling fan, gem positioner and is mounted directly onto the spectrometer; it can also be used with spectrometers of other manufacturers.
The GL Gem SpectrometerTM is a USB 2.0/HID compliant device and does not need a soft-ware driver as many other spectrometers do; the GLGemSpec software is simple to install (only 104 KB; it would work on an old labtop running Windows 98), easy to learn and extremely fast in obtaining and saving both transmission and absorption spectras. They can be imported into other software such as the highly recommended Spekwin32 spectroscopy software which allows for quick viewing, comparison and documentation of a project; we also provide LabVIEW users with VIs for further development on their platforms.
Order now on-line at Gemlab Books & Instruments.
About This Project
The GL Gem Spectrometer system has been under development for several years. My interest in spectroscopy goes back to Bill Hannemann’s book “Video-Spectroscopy: 21st Century Gemology” published in 1988. With 2 years of university physics in my academic background I was intrigued by Bill’s concept and saw its potential but Video Spectroscopy never took off the ground.
Almost 20 years later I started using an Ocean Optics USB 2000 (200 – 850 nm) spectrometer for research in the UV range and a NIR 256-2.5 spectrometer for IR studies – but I must admit that my own GemSpec has quickly replaced them and is being used every day; the $ 24,000 NIR 256 spectrometer has been sold (May 2011).
The maker of the spectrometer is a post-doctoral research scientist working at a local university lab; he is internationally acclaimed for his work and long list of publications about transmission and Raman spectroscopy (in particular its application in stem cell research).
Wolf Kuehn, B.A., M.A., PDP (S.F.U.), Dipl.oec, F.G.G. – GLR&T Project Manager
© 2010 Gemlab Research & Technology, Vancouver, Canada
Up until now we have been testing portable OceanOptics spectrometers in the UV-VIS (200 – 1100 nm) and NIR (850 – 2500 nm) range in the following study areas:
- Absorption and transmission spectroscopy with OceanOptics USB 2000+ miniature spectrometer for gemstone identification such as detection of presence of metals, dye, etc to determine origin, nature and possible treatments.
- Luminescence spectroscopy using an OceanOptics NIR spectrometer and UV-LED illumination for detection of treatments, fillers, etc. used to enhance gemstones.
- Possible use of low powered blue lasers for microscopic tomography studies
New equipment in our research lab
Ocean Optics USB4000 Spectrometer
This is the replacement for the USB 2000 unit.
Tucsen 5.0 MP Color CMOS Camera
|We have added a Tucsen 5.0 MP Color CMOS Camera (2560×1920 pixels) to our trinocular KYOWA microscope connected to a DELL netbook which is also used with our Ocean Optics spectrometers.|
The new Tucsen Tsview software provides a user-friendly platform to control the camera, view and edit images(including fluorescence analysis)and infra-red (IR) macro photography.
The software also allows real-time sharing of images over the Internet. C.I.G. students taking course # 150 Gem Identification can now be assisted through MSN Messenger or SKYPE in their course work.
Ocean Optics USB2000 UV-VIS and NIR256-2.5 Miniature Fiber Optic Spectrometer
The USB2000 couples a low-cost, high-performance 2048-element linear CCD-array detector with an optical bench that’s small enough to fit into the palm of your hand — the same detector and optical bench that have provided superior performance to the users of our 15,000 systems out in the field.
The USB2000 also works the same way as other Ocean Optics spectrometers in that it accepts light energy transmitted through single-strand optical fiber and disperses it via a fixed grating across the linear CCD array detector, which is responsive from 200-850 nm.
Purchase price is US$ 3,061 and $ 253 for the optical fiber assemblies.
Initially we were using the portable Ocean Optics USB2000 Miniature Fiber Optic Spectrometer for colour grading projects.
The new SpectraSuite, the first modular, OS-independent spectroscopy software platform runs on Windows, Linux and MacOS based systems.
The NIR256-2.5 near-infrared spectrometer is designed for applications that require sensitivity in the near-infrared region such as tunable laser wavelength characterization and general NIR spectroscopy. It features a temperature-regulated InGaAs detector array, which is internally cooled for optimum signal-to-noise and sensitivity.
The NR256-2.5 is a less costly, less complex alternative to FT-IR and comparable technologies and acquires data as fast as 10 milliseconds. The spectrometer has an effective range of 850-2500 (enhanced for 2100-2500 nm region). As of May 2011 we have abandoned this project due to lack of funding and available databases for gemstones.
We are cooperating with the Fox Group Inc. – the manufacturer of new UV-LEDs (350 nm and 360 nm, 250 nm in development)- in detecting and analyzing treatments such as fillers. Initial reports will be published soon.
The HL-2000 Tungsten Halogen Light Sources are versatile lamps optimized for the VIS-NIR (360 nm-2000 nm). The lamps feature adjustable focusing of the SMA 905 Connector to maximize light coupling into a fiber. A fan keeps the light sources cool and stable. A built-in filter slot accepts optical filters up to 25.4-mm round or up to 50.8-mm square and up to 3 mm thick.
We have experimented using various immersion liquids to improve the quality of spectras. The optical artifacts caused by the cut of the stone are eliminated by suspending it in a bath of liquid with a refractive index that matches that of the stone.
I followed closely the “Technique for UV-visible-NIR Microspectral Analysis of Gems by CRAIC Technologies”. The full article can be read here.
The choice of the immersion liquid plays an important role in the results obtained from the spectrometer. Glycerin may be an effective immersion liquid for this purpose though it may not match the RI of the stone closely. As a consequence the signal-to-noise ratio was lower and spectral artifacts may still appear; however, glycerin does not degrade over time and has a spectral range which extends deep into the ultraviolet region, it is water soluble and can easily be removed from the gemstone.
The use of an OceanOptics NIR 256-2.5 spectrometer for gem identification.
We have just started some research into the feasibility of NIR spectrometers in gem identification. Near-infrared Spectroscopy (NIRS) is molecular spectroscopy and has been neglected in favour of colourimetry, mid-infrared spectroscopy and techniques based on other special regions. The primary advantage of the NIR region is that absorbencies are lower than in neighbouring regions and generally obey the Beer/Lambert law, i.e., absorbance increases linearly with concentration. This is because NIR absorptions are generally 10-100 times weaker in intensity than the fundamental mid-IR absorption bands.
A crucial step in achieving success is ensuring that the samples have been analyzed as accurately and precisely as conventional techniques allow; these analyses are termed reference analyses. For gem materials this will require calibrations for a select group of specimen such as emerald; once calibrations are obtained unlike most conventional analytical methods, NIRS is non-destructive, requires little or no sample preparation, does not use chemicals and can be operated by non-chemists.
We stopped continuing our NIR studies (as of March 2011) due to the lack of a reference data-base and the high cost of NIR spectrometers.
|The absorption spectrum to the right was obtained from a synthetic flux grown emerald in air and in an immersion liquid (R = 1.65).|
Over the years I have experimented with various setups to get a quick image of an inclusion or a decent close-up of a gemstone. The solution mentioned above with our Kyowa trinocular microscope and a high resolution camera connected to a laptop produces very good results but is time consuming.
After studying Bob’s Rock Shop Product Review on the Raynox Video MicroExplorer and reading Jamey Swishers excellent suggestions at his Photography Help the following ideas present a low-cost portable solution for top quality micro-photography of gems.
As I had already the Raynox Video Explorer and the Panasonic DMC-FZ28 (upon Jamey’s recommendations) I only needed to purchase another Super Macro Conversion Lens MSN-202 with adaptor providing an additional 4x macro-lens. This mounts easily onto the extension tube of the DMC-FZ28 which has produced the best imagery for gemstones and inclusions for me sofar. For illumination I use the built-in fluorescent light in the base of the explorer and/or a Schott flexible fibre-optics ring-light which is connected to a Micro Light FL-3000 with 150 W halogen bulb and directly attached to the macro lens. One can see the reflection of the ring-light in the photo below.
For immersion photography I try to use an immersion dish with a liquid close to the R.I. of the stone. The following images of an emerald were taken (from left to right) with base light only, base light and 50% illumination from ring-light, base light and 100% illumination from above. Another emerald is shown in a “dry” setup using a black disk as background.
The same setup can be used for macro-photography; the macro conversion lens has to be exchanged for the 35x micro lens from the original video-explorer.For the following shots of various gems I used an Ott-Lite True Color flip-light. These images are shown as I took them; I did not enhance them nor crop them.
The Panasonic FZ28 is a versatile camera and the superior optics of the Raynor micro/macro lenses in the above setup produce images which match results from a professional gem microscope costing thousands of dollars; it takes very little time to take a picture and the system is portable.
Wolf Kuehn, B.A., M.A., Dipl.oec, F.G.A., F.G.G. – GLR&T Project Manager
© 2010 Gemlab Research & Technology, Vancouver, Canada – www.gemlab.ws
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