I also have other Wilton gel color and am very happy with them. From the black but I can not say that. The color is not particularly opaque, so I have to use up almost half of the crucible needs to achieve at all a result. And even then, the result is more gray than black. Something black I have thus never get.
However, I am referring to color dough, because maybe it behaves so in marzipan or icing (have read in another review as I do) differently.