As I understand it most of how objects look is because of how photons interact with electrons and photons emitted when excited electrons fall to lower energy levels producing photons.
So if one traps a completely ionized mass of say iron or nickel and drew off the associated electrons what would the remaining plasma look like? To my way of thinking, it would have to be colorless. There is another bit of my brain telling me it can't be so. enlighten me.
It is extremely hard to reach any kind of density of "plasma" of just nuclei - the thought experiment of "drawing off" the electrons would be surprisingly hard in practice, as the net charge gets larger and larger so the energy required to remove one more electron gets astronomical very quickly.
Thus you would have a very low density "plasma" and if there are zero electrons, the mean free path of photons traveling through the medium would be such that there is no reflected light and it would look "black" (very dark grey) in reflected light. Most of the photons would travel right through (it would be mostly transparent).
So yes - most likely no "color" can be observed.
You can get a picture of the iron atom's shadow. You can see the nuclei's and electron's shadow.
