The Spectroscope in Gemology


Step 3: Practical Gemology

Lesson 3

Sometimes, refractive index (RI) and specific gravity (SG) readings alone won’t identify gemstones. More often than not, you’ll need a spectroscope to make a final determination. In a few cases, you can make identifications solely with this fundamental piece of gemological lab equipment. (That saves quite a bit of time). This tool is also a great asset for examining rough gems, when getting RI readings is difficult. Last but not least, sometimes only a spectroscope can distinguish 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 see and the easier it becomes.

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 …

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Full Article Details


Content Length 2845 words
Reading time 14 min 14 sec

Here's what you get if you unlock this article:

  • What Does a Spectroscope Show?
    • Selective Absorption
    • Light Measurements
  • Spectroscope Types
    • Diffraction Grating Spectroscopes
    • Prism Spectroscopes
    • Spectrometers
    • The Budget Option
  • Spectroscope Features
    • Focus
    • Scale
    • Holders
    • Light Sources
    • Full Spectrum Lighting
    • Comparison Prism
    • 2-Tube Spectroscopes
    • Colored Filters
  • Spectroscopic Techniques
    • Transmitted Light
    • Internal Reflection
    • External Reflection
  • Advice for Beginners
  • Advice for all Spectroscope Techniques
  • More Hints for Spectrographic Analysis
  • What You Might See Through a Spectroscope
    • Lines
    • Bands
    • General Absorption
    • Cutoff lines
    • Fluorescent lines
  • Typical Spectra for Various Gemstones
    • Type 1a Diamonds
    • Type 1b Diamonds
    • Maxixe Beryl
    • Aquamarine
    • Emerald
    • Ruby
    • Malaya Garnet

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