Any stone that changes color under different types of light is a rare treat for collectors. Color change garnets show the widest range of transformations in the gem world, with almost any hue possible.
Garnets belong to a complicated family, full of surprises. Color change garnets are no exception. For many years, it was commonly said that garnets come in every color of the rainbow — except blue. Recently, this has been proven false. In the 1990s, garnets that appear blue-green in daylight and purple in incandescent light were discovered in Madagascar. These stones were a mix of predominantly pyrope and spessartite.
Most, but not all, garnets that display color change consist of a mix of pyrope and spessartite, such as those blue gems as well as rare but more accessible malaia garnets. However, garnets from Idaho, primarily mixtures of almandine and pyrope, occasionally show a strong color shift from red to purplish red. Mali garnets, predominantly grossular with some andradite, may also show a color change from grayish green in fluorescent light to brown in incandescent light.
Distinguishing garnet species can be difficult. Keep in mind that color change garnets aren’t a specific garnet species or limited to a specific mixture of species. These gems will display the physical and optical properties of the species or blend to which they belong. These durable stones should also receive the same care and maintenance as all other garnets.