What are Gemstone Identification System?

Raman micro-spectroscopy is an optimal strategy for the assessment of attractive gemstones. The absence of test readiness and the non-damaging nature of the Raman examination make it ideal for the investigation of even high-esteem gemstones. Besides, the micro Raman investigation of a stone gives an interesting record of ID motivations. We will examine the assortment of Raman spectra obtained from various groups of gemstones, looking into spectra from certifiable and counterfeit materials.

Gemstones and semi-significant stones have been adapted for quite a while to make them more splendid, more appealing, and less difficult to work with. One such methodology is heat treating (the most generally perceived) to improve, make sense of, or make an assortment in a stone.

• Amethyst is heated up for citrine.
• Zircon is heated up to clarify the stone for clear white.
• Sapphires are heated up and get shocking pinks and blues.
• Rubies lose a purplish variety while iolite may be turned a dim blue.

Heat treating can similarly be used further to develop the 'assortment change' of gems, for instance, tanzanite. Passing on from stones is moreover an especially typical practice.

• Agate is hued to get pinks, purples, oranges, and blues.
• Chalcedony is moreover hued; dull chalcedony is sold as onyx.
• Light is another ordinary treatment.
• Topaz is at present the most ordinarily lit gemstone (to get various shades and tones of blue).

This is moreover the way that one gets grandly concealed valuable stones. The gem was the principal gemstone to be assortment treated by radiation. The change was by and large accomplished by filling the stone with typical oils; regardless, currently designed saps, for instance, Opticon are as of now being used. Sap filling is much of the time more dependable than the use of standard oils. Opals are habitually offset and emeralds have a long history of break filling due to their pervasiveness and a tendency to be particularly broken or contain various contemplations.

Citrine is the most valuable Quartz gem. Almost all Citrine on the market is heat-treated Amethyst. Natural Citrine is yellow to orange and occurs in much lighter hues than the heat-treated material. In some Amethyst deposits, the Amethyst has been partially or fully changed to brown Citrine by geothermal heating. Citrine may also be produced by heat-treating Smoky Quartz from certain localities. Citrine also closely resembles Topaz. Unfortunately, unscrupulous dealers label Citrine in such a way that unassuming buyers think they are buying the more valuable topaz. It should be understood that any “Topaz” labeled with a prefix (such as Gold Topaz, Brazilian Topaz, and Citrine Topaz) is heat-treated Citrine. The Raman spectra in Figure 2 indicate the difference between the two gemstones. A yellow-colored natural quartz can be passed off as the more expensive topaz (red) by unscrupulous gem dealers.

All natural diamonds are ‘flawed’, often by color or impurities. Most diamonds have some yellow or brown color. Defects mark the diamond as unique. Color centers in diamond photoluminesce (PL) when excited by laser light. A Raman spectrometer used to measure PL is a powerful characterization tool to identify artificially reprocessed, ‘exotic’ colored diamonds. (Figure 3) The diamond grading system is as follows: D and F are colorless, G through J are nearly colorless, K through M are faint yellow or brown, N through Z are light yellow, brown, or grey, and Z’s are fancy yellow or brown.

The spectra of two other gemstones mounted as jewelry are shown in Figure 4. The differences between the green peridot and the purple tanzanite are identifiable in these spectra. In conclusion, Raman is a powerful tool for the identification and qualification of gemstones.