Is that really a color though? I think color is the way we perceive EM radiation, including radio waves. And since we can't perceive actual radio waves with our eyes, I don't think they are a color.
They can be in imagiation.Lots of things that can't be done, seen felt or achieved can be real in imagination.Right now, inside my mind I'm running my hand over the glassy surface of a neutron star!
I did it. I imagined a new colour. Get me the right pencil and ill show you.