We have 6001 Grayish on the walls with light cream ceilings. For a few days after application, it seemed to have a purplish hue during the daytime and depending upon the lighting, would change tints at night. I figured it was a combination of ambient light (blue skies) and the khaki paint underneath. A few days later, the paint dried fully and the purplish tint diminished and it definitely looks grey. I really like the way it changes tones now with different lighting.

you need to get a white base and have them add a couple squirts of pure black. that's it. gray. No blue, no green, no yellow. just black. You don't even need a color chip. 3-4 squirts of black. Ben Moore,Gray Cloud,is just that.