You make the darkest "black wood". Getsome aniline dye (not stain, dye) and apply that to the Dymondwood. If you mix it with alcohol, you can get it diluted all the way to light gray. If you don't dilute it, I'm sure it'll be black enough for you. If you apply the dye after shaping the riser, I can't believe that you'll have any noticable grays due to glue lines. I guess, to make sure, just glue up some scraps, shape them a bit, then dye them. I do think this is the way to get a truly black black. Dymondwood is fine in the oven at 185 degrees. At least is has been on the two bows that I've made. Another option, don't cook the bow. All the heat box does is speed up the setting of the glue. Just clamp it up and leave it in the form for a day or two if you want to cook it.