---
title: "Spectroscope: meaning in gemology"
description: "A spectroscope is a gem-testing instrument that spreads light from a stone into a spectrum. Dark lines and bands show where the stone absorbs."
url: https://digitalgemology.com/learn/glossary/spectroscope
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Gem testing

# Spectroscope

Also called hand spectroscope

A spectroscope is a gem-testing instrument that spreads light from a stone into a spectrum. Dark lines and bands show where the stone absorbs.

## In more detail

A prism or a diffraction grating does the spreading. A grating spreads wavelengths evenly. A prism squeezes the red end and stretches the violet end. The lines often name the coloring element, not the stone.

## How we measure it

Our Spectroscope computes the spectrum from measured spectra on a 1 nm grid, through 1 to 10 mm. You choose lamp light (illuminant A) or daylight (D65). Its prism is a 60° prism of N-SF11 flint glass. It is a teaching model, not a test of a real stone.

## Related terms

- [Absorption spectrum](https://digitalgemology.com/learn/glossary/absorption-spectrum): An absorption spectrum shows which wavelengths of light a stone absorbs. In a spectroscope, the absorbed parts of the spectrum look dark.
- [Absorption line](https://digitalgemology.com/learn/glossary/absorption-line): An absorption line is a narrow dark line in a spectrum, where a stone absorbs a narrow range of wavelengths. An absorption band is a broad dark stretch where it absorbs a wide range.
- [Dispersion](https://digitalgemology.com/learn/glossary/dispersion): Dispersion is how differently a stone bends red and violet light. Gemologists give it as the index difference between the B line (686.7 nm) and the G line (430.8 nm).
- [CIE colorimetry](https://digitalgemology.com/learn/glossary/cie-colorimetry): CIE colorimetry turns a light spectrum into a color by weighting it with standard human color-matching functions. Standard illuminants, such as D65 (daylight) and A (incandescent lamp, 2856 K), define the light.

## Learn more

- [Spectroscope](https://digitalgemology.com/tools/spectroscope)
- [Spectroscope](https://digitalgemology.com/about/how-we-measure/spectroscope)

[All 328 terms](https://digitalgemology.com/learn/glossary)