I believe Gaboon is the blackest. I don't dye it. If some lighter colors show up in it, I leave them.
I tell customers this and never guarentee perfectly jet black ebony. I do my best to seperate and grade it, but at the end of the day, It's wood.
Michael Webb is right - it's wood and not some manufactured product, so there can be light streaks buried beneath the surface. Gabon (or Gaboon) has gotten hard to find, so the quality of color may not be what it once was. I recently had a piece of Indan Ebony that was jet black all the way through.
YMMV
Gary
The darkest ebony I have ever seen is Malagasy ebony from Madagascar. Almost all of it is very dark. In talking to a supplier years ago he said less than 5% of Gaboon they harvested is jet black whereas a very high percentage of Malagasy is. It is very highly prized by the Chinese and very hard to find in the US.
The Jet Black Ebony from Madagascar was the blackest I have seen. Gabon is the more common black stuff we have all used, but not as black as the Madagascar stuff we used to get. Nigerian Ebony can be really black, but as a whole not as black as Gabon.