The science of gemology

Article published at: Mar 13, 2024
The science of gemology
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What is gemology?

Gemology is the science that studies gemstones
and is a branch of mineralogy and, by extension, geology. The word "gemology" comes from the Latin word "gema" which means gemstone.

It is a speciality that focuses on the analysis and certification of the authenticity of a gemstone, as well as the identification of the enhancement treatments it has undergone.

The expert gemologist examines the stones by physical observation, but also with the use of special instruments, and first decides whether the stone is natural or synthetic. If the stone is natural, the gemologist identifies it and then assesses its specific characteristics in order to estimate its commercial value.

Gemologists can identify a gemstone based on certain characteristics and properties, such as cut, colour, quality and clarity. Certain rubies and garnets, for example, may not differ in appearance, but may have different physical properties.

The 4C criteria

A very popular set of criteria is the 4C criteria used in gemology to evaluate diamonds. These are the initial letters of the English words carat (carat, a unit of weight), clarity, colour and cut.

The gemological laboratories

There are many gemological laboratories in the world, and they are usually private or owned by associations. Two of them are the most reputable and have worldwide recognition, the Gemological Institute of America (GIA) and the HRD Antwerp in Belgium. These institutes have branches around the world and provide training and gemology certification degrees to jewellers.

The consumer should be aware of whether the certification of a piece of jewellery comes from a well-known institute, and most importantly should consult the jeweller they trust.

The gemological tools

The gemologist uses several specialized tools to evaluate gemstones. The main one is the microscope and, in most cases, with this instrument he can make a complete assessment of the stone under examination. For example, a microscope can magnify the examined stone 30, 40, 50 and so on times, while the jewellers' specialized lens gives 10 times magnification and the bookstore magnifying glass 5 times.

In addition to the determination of the test stone, the following is measured:

- the angle of refraction of light passing through the stone, using a refractometer,

- the specific gravity when passing through the refractometer through the refractometer, the specific weight,

- the dust line,

- the analysis of white light by spectroscope.

Finally, the estimate of value depends on the clarity, colour, cut, size (carat) and rarity of the stone in relation to all of the above.

In the photo below, KALFIDIS Jewellery's gemologist, Akanthos Kalfidis, who studied at the HRD in Belgium, is evaluating a diamond at the Gemology Station.