The easiest way to ebonize wood is with black dye. Unlike pigment, which is the colorant used in paint and most common stains, dye is transparent so you can apply as much as you want and still see through it. You can get wood totally black using a black dye and still see the grain and figure of the wood underneath.
Using dye to ebonize wood is also far more effective than using a rusty solution of vinegar and iron, which is often suggested.