EXA™ – The Natural Diamond Detector
EXA™ will report you a natural diamond whenever it sees one! Just point the tip of the probe on loose or mounted colorless diamond looking stone and you will know in less than a second if it is a natural diamond or something else.
No specific training is needed, EXA™ can be operated by anyone.
- Recognizes about 98% of natural diamonds by telling “PASS”
- Refers about 2% of natural diamonds for further testing
- Refers 100% of HPHT and CVD-grown synthetic diamonds for further testing
- Refers 100% of diamond simulants for further testing
EXA™ uses advanced spectroscopy for detecting natural diamonds. It works for loose and mounted stones starting from less than 0.005ct, there is no upper size limit.
The system is a standalone desktop instrument with touch screen panel and built-in audio. No PC connection is required.
Important things to know
EXA™ detects natural diamond by analysing it’s photoluminescence spectrum. The samples are illuminated with strong longwave ultraviolet light (LWUV) which is almost invisible yet harmful for eyes. Never look directly in to the probe end. It is advised to use the supplied polycarbonate safety goggles during prolonged use of the instrument.
We have embedded a very sensitive spectrometer inside EXA™ for providing accurate results. For this reason the instrument absolutely hates strong ambient lightning and especially fluorescent tubes. The ”spiky” light of fluorescent tubes pollutes the spectroscopical analysis to the point that many natural stones are referred for further tests (so called false negatives). Please switch off fluorescent tubes during the use of the instrument.
EXA™ is not a diamond type tester, so it very often correctly reports type IIa natural diamonds as natural instead of referring them for further tests. The term natural strictly means that the stonehas been mined from the Earth instead of grown in a factory. Type IIa stone passing the test is a natural diamond but may have been subjected to HPHT-treatment for enhancing its color grade. EXA™can not detect such treatment
Advanced User Mode
EXA™ can be operated in Advanced User Mode which allows experienced gemologist to gain a lot of useful information by looking at gem’s fluorescence spectrum. This mode also allows for increasing testing time for temporary sensitivity boost.In Advanced User Mode EXA™ is a completely new kind of tool in the gemological laboratory; It is a strong longwave ultraviolet lamp on the tip of coaxial flexible probe, combined to a sensitive spectrometer which presents the emission spectrum of fluorescent gems on the screen.
Reference database
EXA™ comes with internal reference database.
Fluorescence spectrum of colorless synthetic CVD-diamond (blue line) compared to the reference (white line) in the library. Note the lack of Cape lines and the SiV- peak at 737 nm.
Fluorescence spectrum of natural pink multi-treated (HPHT-Irradiation-Annealing) type IaAB diamond and similar library item (white line) in database.
The spectrum of colourless CVD-diamond has been zoomed in order to verify the Silicon-Vacancy peak location. The extent of the SiV defect can vary a lot due to the growth conditions.
Fluorescence spectrum of blue CVD-grown and irradiated type IIa synthetic diamond (blue line) with similar library item (white line) in EXA database.
Some examples of the advanced use of EXA™
Natural pink diamond
Most natural pink diamonds having natural color origin can be identified by detecting a peak at 415 nm together with side bands visible in this image. This pattern is typical for natural pink diamonds coming from Argyle mine in Australia. Currently more than 90% of pink diamonds are originating from this mine.
Synthetic & treated pink diamonds
The cause of color in synthetic (both HPHT and CVD-grown) and treated natural pink diamonds differs from natural pink stones having natural color origin. The PL-spectrum is dominated by nitrogen-vacancy centres (575 and/or 638 nm). The example on this image is fluorescence spectrum of pink CVD-grown synthetic diamond.
Treated pink diamonds
Multi-step treated pink diamonds feature a quite unique spectra. The small N3 center (415 nm) and its sidebands reveal the stone was originally a low nitrogen IaAB. HPHT was applied to break down Nitrogen aggregates, Irradiation created vacancies and annealing allowed them to bond to single nitrogen, the resulting nitrogen-vacancy centres (575 and/or 638 nm) are responsible for the pink color.
Still pink but ain’t diamond
Completely different type of fluorescence spectrum such the one above quickly reveals that this stone resembling pink diamond is not a diamond at all. This spectrum belongs to perhaps the most common pink diamond simulant: pink stabilised cubic zirconia (CZ).
Oil fracture filling in emerald
Resin fracture filling in emerald
Corundum; ruby & sapphire
This fluorescence pattern belongs to chromium in corundum. Most corundum, including metamorphic blue sapphire, contains enough chromium for revealing the strongest peak centered at 694 nanometers. Please note there is no difference between the spectra of natural and synthetic corundum.
Alexandrite
Just like in the case of corundum, chromium in chrysoberyl (alexandrite) can be detected by its unique fluorescence pattern. Once again there is no differences between natural and synthetic stones.
Natural spinel
Chromium causes unique pattern also for spinel. This is the famous ‘organ pipes’ emission structure sometimes seen in spinel even with regular spectroscope. It can be seen in all red, pink, orangish and purplish stones.
Heat-treated and synthetic spinel
Heat-treated natural spinel and synthetic (flux,- and Czochralski-grown) spinel exhibits very similar emission pattern as natural untreated spinel. However, the main peak is more broad and shifted towards higher wavelengths. This is extremely useful information as many modern synthetic spinels are totally inclusion free and their detection in microscope may be challenging or impossible.
“Imperial” topaz
This unique fluorescence pattern proves that the sample is topaz and that it contains chromium as coloring agent. A pink or orange coloured topaz NOT having this fluorescence pattern is suspicious – probably it is either irradiated or coated.
Tanzanite
Working with EXA™, tanzanite can be separated from its imitations in less than one second. All tanzanite has the two broad peaks around 700 nanometers, caused by element vanadium.
Tsavorite
Tanzanite’s noble cousin, tsavorite garnet can be readily identified from this fluorescence spectrum. The structure around 700 nanometers caused by vanadium is truly unique for tsavorite.
Malaya- and color change garnets
Malaya- and color change garnets usually contain chromium which causes red fluorescence with this emission pattern
Zircon
Natural colorless or blue zircon is not difficult to identify by a skilled gemologist. Still EXA can do the same job in a fraction of a second. Just memorize this pattern which is caused by rare earth elements.
Warranty
MAGI Warrants to the original purchaser of the EXA™ that the unit will be free from defects in material and workmanship for a period of 12 months from the date of original shipment.
EXA™ contains no user serviceable parts and components. The enclosure is sealed with a holographic label in order to prevent unauthorized maintenance. Any attempt, alteration and modification of the machine and/or the seal not made or formally authorized by MAGI will void and nullify the warranty. The warranty does not cover any of the following conditions:
• MAGI seal and/or serial label has been tampered or removed.
• Damage caused during installation and/or transportation of the unit.
• Damage caused by modification or repairs not authorized or made by MAGI.
• Unusual physical or electrical stress or power fluctuations.
• Normal wear and tear.
• Abuse or improper and unreasonable use, mistreatment or neglect.
Return & Repairs
For warranty returns and repairs, written proof of original purchase date must be provided. The unit returned for repair or replacement must be properly packaged to avoid damage. Warranty repairs will be made, at our option, on-site or at MAGI facility.
Additional Photos
