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LA-ICP-MS: Laser Ablation Inductive Couple Plasma Mass Spectroscopy |
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LA-ICP-MS provides qualitative and quantitative data of chemical elements. The laser unit creates a micron size mark which is barely visible under the microscope even with trained eyes. The particles are carried to the plasma torch and mass spectrometer for analysis. The plasma unit causes atomization and ionization of the atoms. The mass spectrometer measures masses of the elements for identification according to mass to charge ratio.
LA-ICP-MS is a powerful method used in origin determination and detection of treatments in gemstones. One of the most important advantages of this method in our work is the ability to detect Beryllium (Be), a light element that is not detectable by EDXRF. The detection limit of this instrument is 0.05 ppm. |
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EDXRF: Energy Dispersive X-ray fluorescence |
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EDXRF provides qualitative and semi-quantitative chemical data without damaging the sample. X-ray photon un-stabilized an atom. The unstable atom releases energy to return to the stable stage in a form of characteristic X-rays, each being specific to particular elements.
The technique is used in the process of gemstone identification based on its chemical compositions.
Treat - ments such as glass filling and coating can also be detected. In addition, the trace elements in corundum can be quantified.
The quantitative data obtained provides
some insight on corundum source type and origin determinations |
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FTIR: Fourier Transform Infrared Spectroscopy |
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FTIR is routinely used in GIA Research (Thailand). It is a non-destructive technique in which infrared radiation passes through a material causing vibration of the crystal lattice. The energy absorbed and transmitted is measured and transformed into a spectrum. This technique is very useful in treatment identification such as heating in ruby and sapphire, clarity enhancement by oiling or filling in emerald, bleaching and dying in jade. Separation of some natural and synthetic gemstones can also be achieved. |
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RAMAN |
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RAMAN is a light scattering technique named after its inventor, Sir C.V. Raman. In this nondestructive technique, laser beam of visible light is used to cause vibration of the molecules in a gemstone providing spectral information that is unique for each material. The spectrum is compared to an extensive mineral database to identify the gemstone. The technique also allows identification of inclusions inside the gemstone. |
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UV/Vis/NIR |
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This technique analyzes a full range of visible spectrum from ultraviolet to the near infrared. Gemstone absorbs light at different range depending on its natural or treated trace elements or color centers. As a result, it provides information on origin of color. In addition, sapphire source type can be determined. |
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Microscope |
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A gemological microscope is routinely used in the lab. Designed to utilize a variety of illumination techniques, it can help us to investigate the internal microscopic world of gem stones. A lot of information can be extracted from general observations under a gemological microscope. Gemologists can sometimes determine whether a gem is natural or synthetic from its inclusions. Many treatments can be detected using a gemological microscope such as frosted crystals and dissolved silk in ruby and sapphire caused by heat treatment, oil in fractures of an emerald indicating clarity enhancement and color concentration in cracks and pits of jade as an indication of dying. There is no doubt that gemological microscope is invaluable instrument in gemology. |
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