With both the dark_skin and black_skin tags the ebony tag seems a bit redundant, even more so since the black_skin tag specifically mentions ebony coloration.
Given the somewhat subjective nature of trying to decide if a character is African/South American/Indian/Mediterranean/etc from their skin color and that there seems to be only one user actually applying the tag to any posts, perhaps it should be aliased to black_skin or dark_skin.
At the very least, the vague wiki page should be clarified if we keep the tag.