Gurm White as in the color #ffffff or rgb(255,255,255) should not require any dithering. And black, as is the color #000000 or rgb(0,0,0) should require it either.
Dithering occurs when a monitor can't display a certain color, or more precisely a combination of RGB values (which correspond to the amount of light allowed to pass through the RGB subpixels). There's no reason at all that any display that uses 2-bits per pixel or more would need to dither for those two black and white values that I mentioned.
I assumed everyone knew that but perhaps not.
EDIT: Just to clarify, it is not possible to dither for the highest or lowest values a pixel can have. If a monitor can't display rgb(255,255,255) without dithering, then it can't do that with dithering either. This is only completely true for both the values rgb(255,255,255) and rgb(0,0,0).