Colors are, of course, the colors of the adopt! All adopts have up to three (3) colors. Most colors are basic, but there are some gradient and double colors as well to keep things interesting. Colors come in three (3) slots: primary, secondary and tertiary.
Under-Colors: The primary can be replaced with a bases under-color, which will not show unless the base is removed. The under-color replaces the previous primary color and cannot be changed back unless you override the base with a different base or color. See 'Bases' for more about how bases differ from colors!