The color of iron oxide is determined by the oxidative state of the iron atom. 

Iron oxide colors. Iron oxide yellow is a yellow pigment that is used in many applications, including paints, plastics, and cosmetics. It is also known as ferric oxide or hematite. Iron oxide yellow is a natural mineral pigment that is inexpensive and durable. It is also used in food coloring. Iron oxide yellow is resistant to UV rays and salty weather. It is also used in building materials, rubber, asphalt, sports racetracks, paper, and plastic