Why do different colours of toned solar control glass have different solar control properties?

The different colours across the solar control range absorb solar heat to different degrees and is mainly a function of the amount of colourant that is present within the glass mix when each of the products is manufactured. The role of a solar control glass is to control the amount of solar infrared (heat) transmitted through the glass. Whilst this is controlled via reflectance as well as absorption, the amount of heat absorbed by the glass will be determined by the amount and properties of the colourant within the glass.