There is actually no chemically manufactured colour that does not also occur in the natural world, however ‘natural colour’ is usually used to refer specifically to colours that have been obtained from the natural world, i.e.
a) Animal- such as red cochineal from bugs, blue – black ink from squid, black from burned bones.
b) Mineral – dug up or mined from the ground,as earth pigments or mineral deposits or from stone by crushing. Such as the ochres, lead, lime, lapis lazuli, titanium white, sand, zinc, marble…..
c) Vegetal – dyes derived from plant materials, e.g. indigo, weld, tea, coffee, onion skins, lac, turmeric, ginger, saffron, etc. …
All natural colours recall an aspect of nature that gives name to the tone: sand, wheat, sky, sea green, heather, thames mud, clotted cream, coffee, cacao, savannah, forest, ice, peach, apricot, rose, nutmeg, mace, chocolate, bone black, sea blue, nut brown… ad infinitum.
No chemical colour can compete with a natural pigment for beauty and timelessness, the best a chemical can do is to perfectly match just one of the myriad nuances that every pigment contains.