Crystals occur in a range of colors, from colorless to having multihued shades like a rainbow. The color of crystals has long fascinated and drawn humans to them. There is a crystal for every color in the rainbow and beyond, it seems.
Crystals are transparent, translucent or opaque depending on various factors such as impurities or type. In general, transparent crystals are valued more highly than opaque crystals, but there are many exceptions to this as well. You might think of jade or rubies, which are opaque, but having a high value.
What causes a crystal to have a certain color? Crystal coloring normally is either idiochromatic or allochromatic in nature. Now, maybe some of you might be wondering what those terms mean. So without further ado…
Definition of idiochromatic – Having the same color on all the time, due to a specific mineral present in the structure. Examples: azurite, sulphur.
Definition of allochromatic – Having a different color even though it may be the same mineral, due to the presence of other various mineral impurities which may differ depending on the location of the crystal. Examples: quartz variants, sapphires, diamonds
There are also crystals that look iridescent; this is caused by the internal structure of their surface which bends light in such a way that it looks a different color depending on the angle with which you view them. An example is labradorite.