I'm a beginning soapmaker, and for me I think it's important to do all natural colorants. However, they're not often very bright. There's some argument as to oxides on natural soaps because they are derived from natural materials, but extracted in a lab to exclude possibly harmful components of the natural state of the oxide.

Theres no industry regulation on "all natural" but I feel like it should include solely essential oils and colorants found in nature. I'm still learning where oxides have a place there, since many "all natural" lines use them.