Caran d'Ache Luminance can be considered the best and most expensive pencils on the planet.
Their quality is superb and they are light fast. The pencils are pretty opaque, and that is the reason that I bought a some yellow, green, blue and a white pencils.
I recently received a box of 76 Luminance pencils and am now exploring them.
My first impression of these pencils is that they are one of a kind.
For colouring in colouring books, you do not really need this high quality pencil.
If you want to frame your art work and have it in perfect condition without the colours slowly fading away, then these pencils are the best choice.