from:   the official AKC Brussels Griffon Standard

Belge: black and reddish brown mixed, usually with black mask and whiskers;

AMPLIFICATION: The name Belge comes from the native standard. This color is rarely seen to perfection. It consists of a two-colored hair shaft (banded, or mixed with rich red and black). The result is a smoky or smutty overall appearance. The Belge is often enhanced by a black mask and ears. Since the Belge can carry recessive genes for black and tans, they may have tan points.

UNDESIRABLE: Pronounced shading or saddling in overall coat color.