When I started to build some complementary pieces for my Master Maze dungeon I had a hard time to come up with a nice matching color scheme. Therefore I think it is worth to share my findings.
Use a black primer. This provides a first nice coat of black.
For the base color mix black and white. Just put two blobs of paint on your palette and start mixing until you get the right tone. Now add some ochre. Yes ochre. Take care that you do not add too much. If you add too much ochre, your color will become too greenish. (Take care there exists yellow ochre and red ochre. I refer to yellow ochre. In most cases a color labelled „ochre“ will be yellow ochre.)
For the brown stones just use a matching brown of your choice. I often use P3’s Beast Hide. Nevertheless Dwarven Forge’s Earth Stone is a viable option.
Here it comes. For your drybrush use some kind of bone color. My favorite of choice is P3’s Jack Bone, but I am pretty sure that every bone color works. Just take care that the color is not too white.
If you find a better match, please let me know and send me a comment.