Characteristics of gemstones
The color of the gem is uniform and single. Because the gem is a single crystal, its chemical elements strictly abide by the composition law and relatively repel impurity ions, so its chemical composition is relatively uniform and pure, so the color of the gem is single, that is, the color of the gem is caused by one or two relatively fixed ions.
For example, the color of ruby is caused by cr ions, and the color of sapphire is caused by iron and titanium ions. The color of gemstones is relatively uniform, that is, the color of gemstones is basically distributed throughout the crystal. Gemstones are composed of one or two pigment ions with relatively uniform colors.