Your Gemologist: What You Should Know

The role of gemologist is crucial to the gem trade. A gemologist is someone who has trained professionally at an accredited institution in colored stone identification and colored stone grading. The training may also include diamond grading. Gemologists may work in gemological laboratories, in retail jewelry stores, and in manufacturing organizations using their knowledge in a variety of fields including purchasing and quality control.

If you are purchasing a gemstone from a jewelry store in the United States, you may encounter a jeweler with the initials “G.G.” or “FGA” on their business card. This refers to the jeweler’s status as a Graduate Gemologist, and means that they have successfully completed advanced professional training either through distance education or in residence at the Gemological Institute of America, or GIA. GIA is considered one of the leading authorities in gemology and developed the grading systems widely accepted and commonly used in the jewelry industry today. “FGA” indicates the jeweler holds a diploma from the Gemmological Association of Great Britain. The designation “R.G.” or “R.G.A” indicates the jeweler completed training through the International School of Gemology. The initials are a reference to Registered Gemologist and Registered Gemologist/Appraiser, respectively and are not as highly regarded as the G.G. or FGA. There are many other gem labs across the country that offer courses of study, professional development, and certificate programs including the International Gemmological Institute (IGI) and the Diamond Council of America (DCA).

What a Gemologist Does

A gemologist is an expert that is able to identify and classify gemstones of many varieties. A trained gemologist will be able to discern visible and measurable difference in minerals and can determine if a gemstone is natural, synthetic, was subjected to treatment, and even the country of origin. This is accomplished using a variety of tools, including some very sophisticated equipment. The gemologist will also take careful measurements to the 1/100th of a millimeter and verify the carat weight.

Tools of the Gemologist

  • Microscope: The microscope is used for gem identification and the identification of internal and surface characteristics. Gemstone grading is done at 10x magnifications, although a gemologist may view stones at much higher power to determine treatments and characteristics
  • Loupe: A handheld magnification tool, the loupe is used for identification and grading in much the same manner as the microscope. If you are new to gemstone shopping, it is important to familiarize yourself with correct use of the loupe. Hold the loupe in your left hand close to your eye, and using gem tweezers, bring the gemstone up to the loupe until it is in focus. Learn to discern with your own eye and become a connoisseur of gemstones.
  • Micrometer: Used for precise measurements, the gemologist will use a micrometer such as a Leveridge gauge to determine dimensions such as average girdle diameter, total depth, and length and width.
  • Refractometer: Each gemstone will bend light in a particular way. The refractometer is used to measure the refractive index, or RI which is a key indicator of a gemstone’s identity as well as measure the optic sign.
  • Spectroscope: Measures the amount and type of light absorption in a gemstone. The two types of spectroscopes used are diffraction grating and prism.
  • Polarisope: Used to make determinations regarding the optic properties of gemstones, the polariscope is an asset when distinguishing natural gemstones from synthetics.
  • Heavy liquids: Used to determine the specific gravity of gemstones. Gemstones immersed in heavy liquids must be un-mounted or “loose” gemstones for specific gravity to be determined.

The gemologist that you choose to work with should be a third party. A third party would be an impartial observer of the gemstone and would not have a stake in its sale. Having a gemstone certified by an outside lab, or third party, is a safeguard against any misrepresentation on the part of the seller. It does not hurt to be wary of in-store appraisals. While gemstone certification can be an added expense, certificates are often worth the peace of mind that comes from the knowledge that you are getting scientific information from a trained professional. Have you worked with a gemologist? Let us know how you chose your gemologist and what your experience was like. If you are looking for a gemologist, let us connect you with reputable gem labs. Would you insist on getting your gemstone certified by a third party? Why or why not?

Read more posts from the Gemstone Buying Guide series