What colour is an ion?

To be perfectly accurate, the colour depends on the element, the oxidation state AND on the ligands surrounding the element. For example, Cu2+ ions are light blue when dissolved in water (i.e. surrounded by H2O ligands) but are dark blue when dissolved in ammonia (i.e. when surrounded by NH3 ligands).

Most ions are colourless (ie give white crystals as solids) However Transition metal ions are characterised by being coloured, eg Copper ions Cu2+ are blue, Nickel ions Ni 2+

Transition metals have different oxidation states with different coloured ions, eg Iron III (Fe 2+) is Pale green,iron IIII (Fe 3+) is yellow/orange/brown. There are lots more examples but particular ions are the same colour no matter which compound they are in- Copper sulphate and copper nitrate are both blue.

Depends on the ion and the electronic transitions it can undergo. Most main group ions are colorless due to no transitions corresponding to wavelengths of visible light, while many transition group element ions are colored due to d-d (technically Laporte forbidden) transitions.

Color of the ions depends on the element as well its charge.

Specify the ion and charge

All ions are created equal. It may be a sign of your unconscious racialism. Stop worrying about the colour of your ions; worry about the content of their character.

Depends what it's attached to. The various oxidation states of manganese, for example, can go between colourless, green or bright purple.

It depends on which one.

Coloured.