Well then if not black. Have the current purple be Violet and an new Purple be Indigo.
That way ignoring the black cores and Light Blue/Cyan and Light Red/Magenta
We would have Red, Orange, Yellow, Green, Blue, Indigo and Violet to cover the visible light spectrum, plus hopefully White and metallic colors like Gold and Silver.
Then you have darker shades or mixed shades like Dark Green or Aqua