I see blue, blue-black and black pigment inks mentioned here, but other colours not so much. So I went hunting and here's what I found:
Birmingham Pens, which, unfortunately, do not ship internationally
kakimori ink
Kala Ink
Mitasanshodo Sumi inks Made by KURETAKI for fountain pen use
Rohrer & Klinger sketchINK
Sailor Storia
If you know of others, please add.