Although many rabbis are lenient about certain shades of brown on a hefsek and on the bedikot during the seven clean days, there are shades of brown that do render a woman niddah. Light brown, the shade of coffee with milk or lighter, with no hint of red, is acceptable. Darker shades of brown, or browns with a reddish tint, are questionable and require evaluation by a halachic authority.

If you will not be able to consult today, the first day of the seven clean days, before sunset, make sure to do your afternoon bedikah so that it can be a new hefsek if you need it. If the original hefsek turns out to be valid then the afternoon bedikah will be a day 1 bedikah of the seven clean days.