Cafè is a smokey dark brown color. It is great for any shading, together with Tiger's Eye (if you want you brown to be medium to dark value) or together with Red Pepper (orange-red color corrector) for more dark value, yet warm brown results. Proportion can be equal or may vary.
It is also great by itself for clients that want grey shades instead of brown for their shadows and for those, that are very faint and pale naturally, you can use it instead of black for the lash line enhancement.