The conversion to Refined changes the colour dramatically in some cases. For example, look at this Metamorphic:
The rocks and stones look as you’d expect and then… apart from the weird shiny effect I figured was a bug, look at the difference in colour tone. I didn’t harvest hundreds of almost black rock to process into almost black stone to get a light grey refined rock. Is this WAI?
It is the same colour, just has high specular, and as it stands our lighting model is not at all energy conserving, so specular always makes objects brighter.
The only explanation I can think of for this is, that it behaves like slate in real live, an oily stone which gets really shiny when polished. But I definitely agree it is very odd the first time you get them.
I used them as “fake metal” in my build 
Thanks, that’s interesting. Do you think there will be changes to the lighting in time that will preserve the mined colour more? Or is this intended? Ta!
It’ll change in time, whether with shader rework or texture rework or both.
Thanks, I will keep hold of the processed blocks then! Much obliged.
Really looking forward to this change! 
yep. i hate that the black refined stops looking black.