I wonder if there are varieties/species of Coco and the word is used rather in a general way? It might account for the marked differences in colour and grain? There are of course significant differences between Ebony colouration depending on where it's grown, age of tree etc.
A lot of reddish Coco ends up dark in short measure and really looks like Ebony, will be interesting to see how your examples age-if they are exposed to significant daylight. I agree, the variety is alluring.
Here's a 68 White Owl that was given to me used , by somebody who no longer posts, I then gave it to another person who I believe gave it to Charlie C. I still have the tube....looks very Ebony like to me.