As a biologist as well as a painter, I think the rainbow is a good thing to remember. Colour is white light with certain wavelengths removed or absorbed, and our eyes have developed using the available wavelengths in the visible spectrum. I love your optimistic imaginative wish for a 'new colour', but I also love the way that all the paint pigments we do have can interact to create such lovely secondary and tertiary colours when mixed.

Thanks Alan, rainbows are full of beautiful colours, but I wanted another colour that was not mixable from the Red, Yellow and Blue primaries that we know so well. Most of the rainbow colours apart from Red, Yellow and Blue we can approximate by mixing the three available colours. Can't imagine it yet but you never know.

Have a look at a rainbow. All the available colours are already there.