All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
A woman recognizes purity from menses by one of the two following signs: (A) dryness, which is when a woman inserts a cotton pad in her vagina and it comes out clean without any traces of blood, or yellowness, or brownness; (B) whiteness, which is a white discharge known by women that indicates the end of menses.
As long as a woman notices yellowish or brownish discharges, then her menses did not finish, so she has to wait until these discharges stop and sees purity with one of the criteria that we have mentioned above.
Allah knows best.