Tell me please what is the most natural way to say the following.
The colour black is my favourite of all colours.
The black colour is my favourite colour.
Is the use of the definite article correct in the sentences, if it is not, then why?
The colour black refers to the color itself, as color.
My favorite color is the color black.
The black colour refers (colloquially) to something that is black.
Which car do you like, the red or the black?
-- I like the black color.
It's synonymous with "the black-colored one" or "the one that is black".
The black color can also refer informally to the color as an attribute of something:
Do you like this car?
-- I do like the black color, but I'm not fond of sedans.
There, "the black color" is synonymous with "its black color" or "the particular quality of blackness of its paint".