I’ve been doing some studies exploring what colours will work best for “black” sheep, such as Hebridean. Enter perlyne black (with its green undertones), burnt umber, earthy greens and golds, and blues (yes, Prussian blue, but also phthalo). Golden lower layers, left to dry and then painted over wet-into-wet with various darks. Darks with more darks, then touch of titanium white to create greys. Trying to differentiate head from body, whether tone or texture is the way to go.
About the only certainty is that a tube of black won’t suffice, but I knew that already and this journey on the dark side of colour shall continue.