Here's some beautiful cherry crown on a job I was fixing after the original installer completely botched the job. Had to scribe almost 1/2" to the roof! Lucky it was 5" crown
Best way I know to color wood black... black as coal. Use this brand, it has a little shellac in it. Speedball Super Black India Ink
You can get a super dark black using steel wool dissolved in vinegar. It works best on woods with higher tannin content. This can be worked around by brewing up some really strong tea and rubbing that on the wood first.
I don't think the steel wool and vinigar would have worked as well on this walnut. Here is the video I followed.