A handheld spectroscope for visible light shows the absorption lines of the elements involved in producing its color. It helps to separate ruby (chrome) against red or pink sapphire (iron) to name only one example

This tool requires a good training and an appropriate light source.
Colorless stones show no absorption spectrum
The sunlight shows a typical absorption spectrum, the Fraunhofersche lines.
Fluorescence lamps show an emission spectrum

For demonstration you may examinate besides gemstones also liquids or flames colored by metal-salts.

Main Features