Here is another source of Forskolin, at 98% purity, and it is described as "off white."
Forskolin in such a pure for is rare (and expensive) so the brown may be attributed to a powder that other companies use to "water it down"
I can vouch for the effectiveness of BBS C-Bolic. My capsules also contained a white powder but used over a 10 week period they definitely helped me lean out. Make sure you drink extra water when using C-Bolic as it has a mild diuretic effect.