I was thinking about Jade-15's coal soap:
And I want to make some too! After all, Christmas is only 350 something days away! I thought that it might be a good idea to make soap with an FO that will turn it VERY VERY dark brown, and then bump it over into black with a small amount of color, vs trying to turn a white soap black.
What FOs do you love that discolor VERY dark? I may go with MO Vanilla Milk, though the Nurture version (vanilla cream) doesn't appear to discolor very dark in their photos.
I have observed that gelling, or even OP, seems to really increase the discoloration of some FOs, so it needs to be an FO that stands up to high temps. For example, Fragrance Buddy Blackberry Jam Butter Cookie discolored VERY dark for me, but the scent just isn't nearly as good as OOB.