It is fond of natural gem that unique Colour and precious few, so the prices is expensive. However, due to profit-driven, criminals never stopped imitation and fake gems. As technology advances, more and more clever way of imitation, which can muddle many test equipment. In contrast, the use of spectroscopy to identify stones, simple, accurate identification, the process quickly and so on. The following example will show you the Ocean Optics spectrometer in gem identification of advantages:
Identification of orange sapphire
Orange or yellow sapphire is extremely rare for criminals through the beryllium scattering corundum (Be-diffusion) process can be made of a high degree of simulation of the orange sapphire, previously used LA-ICP-MS (laser ablation induced plasma mass spectrometry) or SIMS (secondary particle mass spectrometry) method to identify the authenticity of sapphire, but this experiment only in the identification of rare professional gemstone identification laboratory, Zinc oxide and the sample has a destructive, time-consuming and expensive.
Swiss Gemmological Association for its first use OceanOptics special SSEF GemLIBSTM systems, respectively, with natural sapphire after beryllium scattering process to test, by pulsed Nd: YAG laser output wavelength of 1064nm, pulse width of 7ns, single pulse energy of 100mJ laser focused on the sample, inducing damage resulting plasma, then a multi-channel spectrometer to collect spectral data, Titanium dioxide to achieve a spectrometer covering 200-980nm wavelength range 0.1nm spectral resolution measurements. Experimental results show that, according to the beryllium in 313.042 and 313.107nm measured at the peak levels of beryllium samples contrast, natural yellow sapphire in the beryllium content is very low (<2ppm), and after the scattering process of beryllium in the beryllium content of pseudo-sapphire is very high (> 5ppm). The association also simultaneously applied LA-ICP-MS and SIMS methods for beryllium content of the stones measured, comparing the above two methods, SSEF GemLIBSTM system can be reduced by controlling the laser energy extent of the damage to the sample to obtain a wide spectral range (200-980nm ) under high-resolution (0.1nm) detection, a simple and fast sample preparation and spectral analysis set (only a few microseconds of the laser lag time), while more convenient and cheaper. Therefore, the application of LIBS system in the quantitative detection of beryllium content, to achieve the authenticity of identification of sapphire has much room for development.
Identification of Tahitian black pearls
Artificially colored black pearls and Tahitian black pearls look similar, using Ocean Optics USB2000 spectrometer with the sample relative to the visible absorption spectrum of laser Raman spectroscopy, can be quickly and easily identify the authenticity of the Black Pearl. Tahitian pearls no matter how natural hue, have three characteristic absorption bands fixed location (a band 407-412nm, b with the 495-498nm, c band 702nm), Magnesia the width of each absorption band depends on the hue of pearl and with color; and artificially colored black pearl because of its raw material is different, so its visible absorption spectrum features no rules to follow.
Of artificial coloring and Tahitian Black Pearl Black Pearl for microscopic laser Raman spectroscopy, experimental results are as follows: As the two main components are aragonite, so the Raman spectrum have significant Raman spectra of aragonite , and Tahitian black pearls because they contain black organic pigment, caused in 1100-1650cm-1 occurring at a group of the complex envelope of each Raman spectrum, and dyed freshwater pearls black pearl multi-use, do not have the package network lines, and because it contains carotenoids, so show the corresponding Raman peak (1130,1523 cm-1), its characteristics and Tahitian black pearls significantly different.
Thus, according to the visible absorption spectroscopy and laser Raman spectroscopy to identify the authenticity of Tahitian black pearls.
Identification of blue topaz
Blue Topaz is a precious gem, but the colorless topaz yield rich. Method of color change by irradiation (gamma rays, charged particles, fast neutrons) can be colorless topaz to blue, change the color of topaz color stability, hardness, density, Nickel oxide refractive index and other physical and chemical properties almost consistent with the change color before. Currently used UV fluorescence test can distinguish between the initial and change the color of natural topaz: Natural Topaz variable intensity of UV fluorescence, and all change color under UV irradiation Topaz naked eye can not identify the fluorescence.
In view of these results, the use of cathode-ray excitation force stronger instead of UV, and use the Ocean Optics USB2000 spectrometer to collect the cathode luminescence spectra. Experiments show that the natural blue topaz is the luminous intensity of the fluorescence change color three times Topaz, Neodymium fluoride natural colorless topaz is also significantly higher than the luminous intensity color change Topaz (20-30counts: 15counts).
Thus researchers can identify the following steps to the authenticity of the blue topaz: the first measured the fluorescence intensity of ultraviolet, high intensity for natural topaz, or re-cathodoluminescence measurement, natural contrast the cathodoluminescence spectra of Topaz can identify the authenticity of the sample Topaz (with a really natural blue topaz spectral calibration).