Benefits & Applications

This tool can detect gem treatments like irradiated stones from natural colored diamond as well as dyed Jadeite from naturally colored Jadeite.

The spectroscope is a tool for examining which parts of white light are absorbed by a gemstone (as well as by other materials). Materials can absorb parts fall within the visible range and that absorbed part will influence the color of the material.

When a gemstone is observed with a spectroscope the absorbed parts show as dark lines or bands in the spectroscope image.


The prism spectroscope is based on dispersion. The light enters through a narrow slit (some models allow you to adjust the width of the slit) and then it is dispersed through a series of prisms. Some models have an attachment with a built-in scale.

These models are generally more expensive than their diffraction type. Because prism spectroscopes are based on dispersion, the blue area of the spectrum is more spread out and the red parts are more condensed than the diffraction grating types.


  • Triplet prism.
  • High resolution.
  • Adjustable focus.
  • Special design to avoid reflecting interference.
  • Black appearance packed in a leather package.

Use of spectroscope

  • Proper use of the spectroscope and lighting is vital when wanting to see good spectra of gemstones.
  • The most widely used technique is to make use of reflected light. Light enters the pavilion of a gemstone at an angle and the spectroscope should be placed at the same angle on the other side. The light will travel its longest possible path in this way, picking up the most color.
  • To prevent the background on which the stone lies from causing false readings, one should use a black non-reflective underground such as a small piece of black velvet.
  • Another technique is to position the gemstone and the light source (penlight) in one hand in such a way the light source illuminates the gem from behind thus, viewing the gemstone in transmitted light.
  • There are nice spectroscopes stands (some with built-in illumination) on the market but gaining some experience eliminates the need for them.
  • For the new user, it is recommended to start with a gemstone that produces a clear absorption spectrum such as synthetic ruby.