Iron oxide red is a naturally occurring mineral pigment that is sometimes listed as CI 77491 on the colour index. It is a deep red-brown, rust-coloured pigment that's commonly used in cosmetic and personal care products as a colourant. Whilst it does occur naturally, the stuff we use is made in a lab to ensure it is sustainably and ethically sourced, and free of impurities to be safe for applications on the skin.