Powdery flakes that are dyed are known as Micas. They are shimmery and often times sparkly. Micas come in many colors and some are iridescent which means they are dyed a different color on each side. There are dozens of color options available. Micas come as a powder so they do require dilution before adding them to soaps and cosmetics.
Oxides are pigments which are known to be non-bleeding colorants. Available in powdered form they can be diluted in alcohol or glycerin as a liquid colorant. Oxides are often opaque but on occasion they may also be semi-transparent to clear.
The beauty and excitement of Micas and Oxides comes from testing and experimenting how your colorants look in soaps and cosmetics!