Less Than 72 Hours of Bleeding and the Colour

1. If the flow of blood was for 3 days, but not 3 nights, then too it is not haidh; it is istihaadhah. For example, the bleeding started on Friday morning, and it stopped on Sunday night after Maghrib.
2. If the bleeding was just a little less than 3 days and 3 nights (72 hours), it is not haidh; it is istihaadhah. Example: Bleeding started at sunrise time on Friday morning and stopped on Monday morning just before the sunrise.
3. During the period of haidh whatever the colour of the blood is, be it red, yellow, green, brown or black, it is haidh.

(Behshti Zewar)