@Sdmitch
courage that will be a very cool plugin! 😎
(if Kirril2008 don't make it before)

@Jeff
Thanks for precisions, i had suspected that, so that is a truelly tricky Rhino plugin! ☀
(i believe i can make the same with Moi, I will see that 😄

perfect ... you'r the champion.
thank you

thank you , i dont know how i forget this command

WOW! the designs are really elegant.

Reread what I wrote...
It works on ALL materials, making the RGB values 235 maximum; thus 'toning down' the hue of every color that has an RGB value > 235.
To use this one-liner code... open the 'Ruby Console' in SketchUp [via the SketchUp > Windows menu] and the copy/paste the whole of the line of the code into the bottom area of the 'Ruby Console', then press the <enter> key to run it.
All materials are changed [it's relatively fast].
You should see the RGB change in any material you 'Edit' in the Materials Browser, if any value was > 235 it will now be 235...
It is one-step-undo-able - e.g. if you decide you don't like the changes.

You could save the one-line of text into a text file for easier use later on...

do you have only maxwell for sketchup or the full package?
With the full version you can export as mxs from max and then use it as mxs reference in sketchup.
Or import the sketchup scene in max, place your objects and merge the two scenes in studio.