Using the Spectroscope

The spectroscope is also a great asset for examining rough gems, when getting RI readings is difficult, and detecting some treatments. In some cases, only a spectroscope can detect if a gem’s color is natural, dyed, or irradiated.

As with all the other instruments in your gemology lab, practice makes mastery. The more you use your spectroscope, the more you’ll learn to see. Soon, you’ll find yourself conducting tests quickly and easily.

What Does a Spectroscope Show?

Selective Absorption

Natural, white light contains all the hues of the rainbow. Colored gemstones absorb some of the light that passes through them or reflect it from their surface. This process is called selective absorption.

A spectroscope will show you the wavelengths of light emitted, or reflected, from a gem. The absorbed wavelengths of light, on the other hand, will appear as a darker shade of color or black. Since some absorption patterns are distinctive, they prove useful for gem identification.

Light Measurements

When using a spectroscope, we need to define light wavelengths in precise units.

In the mid 1800s, Anders Jonas Ångström, a Swedish pioneer in physics, developed the…

Donald Clark, CSM IMG

The late Donald Clark, CSM founded the International Gem Society in 1998. Donald started in the gem and jewelry industry in 1976. He received his formal gemology training from the Gemological Institute of America (GIA) and the American Society of Gemcutters (ASG). The letters “CSM” after his name stood for Certified Supreme Master Gemcutter, a designation of Wykoff’s ASG which has often been referred to as the doctorate of gem cutting. The American Society of Gemcutters only had 54 people reach this level. Along with dozens of articles for leading trade magazines, Donald authored the book “Modern Faceting, the Easy Way.”

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