• Gemological microscopic study of the internal structure is used to determine whether a gem is synthetic or natural by revealing natural fluid inclusions or partially melted
    exogenous crystals that are evidence of heat treatment to enhance color.

  • Identification by inclusions[edit] Three inclusion phases in rock crystal quartz Inclusions can help gemologists to determine whether or not a gemstone is natural, synthetic
    or treated (i.e.

  • The spectroscopic analysis of cut gemstones also allows a gemologist to understand the atomic structure and identify its origin, which is a major factor in valuing a gemstone.

  • Gemstones of similar color undergo non-destructive optical testing until there is only one possible identity.

  • Likewise, natural stones, particularly beryl minerals, show small flaws – short planar cracks where the direction of the crystalline orientation in the gem abruptly changes.

  • Heavy liquids with a known specific gravity are used to test loose gemstones.

  • When the gemstones are in a rough state, the gemologist studies the external structure; the host rock and mineral association; and natural and polished color.

  • This can be measured and thus used to determine the gem’s identity.

  • [4] There are now numerous gem laboratories around the world requiring ever more advanced equipment and experience to identify the new challenges – such as treatments to gems,
    new synthetics, and other new materials.

  • Analysis and estimation in the gemstone trade usually have to take place on site.

  • The geological environment they are created in influences the overall process so that although the basics can be identified, the presence of chemical “impurities”, and substitutions
    along with structural imperfections create “individuals”.

  • Identification by spectroscopy[edit] This method uses a similar principle to how a prism works to separate white light into its component colors.

  • Identification by specific gravity[edit] Specific gravity, also known as relative density, varies depending upon the chemical composition and crystal structure type.

  • Gemological instruments Gemologists use a variety of tools and equipment which allow for the accurate tests to be performed in order to identify a gemstone by its specific
    characteristics and properties.

  • Identification by flaws and striations[edit] The curvature observed in this synthetic color-change sapphire is due to a process known as the Verneuil process or, flame fusion.

  • Specific gravity is measured by comparing the weight of the gem in air with the weight of the gem suspended in water.

  • Initially, the stone is identified by its color, refractive index, optical character, specific gravity, and examination of internal characteristics under magnification.


Works Cited

[‘o “Gemologist”. Dictionary of occupational titles. Photius Coutsoukis and Information Technology Associates. 2003. Retrieved 2009-11-08.
o ^ “An introduction to gemology”. International Gem Society. Retrieved 2017-08-28.
o ^ “History”. Gemmological
Association of Great Britain (Gem-A).
o ^ Read, Peter G. (2005). Gemmology. Butterworth-Heinemann. ISBN 9780750664493.
o ^ “Institute of Gem Trading”. Institute of Gem Trading. Thailand. Retrieved 2019-10-13.
o ^ “The Journal of Gemmology”.
Gemmological Association of Great Britain (Gem-A) (subscription page).
Photo credit:’]