How can I make a circle which changes its colour with its properties? I show in the attached figure what I mean.

So I modelled how the mositure changes inside a spherical particle as a function of the particle's radius.

I have a lot of data in function of the radius, I can make a 2D x-y figure but I want to make more visible like in the attached picture.

Do you guys have any idea how to make it?

Thanks a lot in advance!