I'm trying (still) to create accurate representations of colors our company paints their products, in order to put the 3d renderings on the website.  I'm having trouble with the illumination and brightness settings in general. 

I've got all the colors based on the RGB values, but they just don't look right when put into a model, no matter how I try to change the illumination and specularity and all those settings. 

Is there something I'm missing in trying to match these appearances?  Like maybe the right way to do it is to use a particular scene with set illumination values, and modify the color based on that? 

Any help would be appreciated, even though I'm pretty sure I'm not explaining myself all that well