Indian ringneck colours

I am a hopeless macaw fan, BUT I am thinking about getting some IRN's as well.

I would be really grateful, if you could tell and show me the different IRN colours. What is the "natural" colour?

Are the colours different species or are they variations within the breed? Ie. is it a hybrid, if two colours breed?

I hope you can help a hopefully future IRN owner to have as much information as possible to make the right choice before purchasing another bird :)