1 Absorption Spectrum
This is the scale that was created to easily classify the various types of gems through means of identifying the precise bands of lighting that would either pass through the gem, or get absorbed and disperse into the colours of the spectrum. This method is used to identify gems and is also useful in weeding out the imitations. Various gems host differing absorption spectra, which aids the gemmologist in easily classifying similar groups of gems together. The tool used to determine the absorption spectrum of a mineral is a spectroscope.