Does She or Doesn’t She?
The question is not about whether she dyes her hair or not, but whether Rivka Imeinu received Prophecy or not.

At the beginning of the sedra, when Rivka is experiencing turmoil within her womb, she goes “to ask G-d”. Commentaries explain that she went to consult SHEIM, son of No’ach, who was a prophet. When the pasuk tells us that G-d spoke to Rivka, Rashi jumps to explain that He spoke via SHEIM, who received G-d’s message about the two nations that were destined to come from the twins she was carrying. Commentaries on Rashi ask why he “felt compelled” to explain that G-d’s communication to Rivka was through an agent, when the plain meaning of the words indicate that He spoke to her directly. They answer that Rashi was concerned about the list in the Gemara of the 48 prophets and the 7 prophetesses — Rivka is not on that list. Conclusion based on Rashi: Rivka did not receive NEVU’A, prophecy.

But that’s not the final word on the subject. When Rivka orchestrates the deception of Yitzchak by Yaakov, who poses as Eisav to receive the bracha that really should be Yaakov’s in the first place, Yaakov hesitates and expresses his fear that his father will feel his smooth skin and discover the deception and curse, rather than bless Yaakov. (Long sentence, but I hope you all followed.) Rivka says to Yaakov that if that happens, the curse shall be upon her, not on Yaakov. Did you ever wonder why this would calm Yaakov’s anxiety? Would he be okay with Rivka being cursed?

Targum Onkeles give an interesting spin on the situation. Rivka’s words were: ALAI KIL’LATCHA BNEI. The Tar- gum, which is most often a straight Aramaic translation of the words of the Torah, in this case adds a crucial phrase, which is not at all indicated from the Written Word. He says: And his mother said to him - to me it was said via prophecy that there will be no curse placed upon you... just do as I say. If we accept this presentation, the next pasuk fits well. And he went, and he took, and he brought... Yaakov, without another word, springs into action. Three verbs in a row convey an immediate compliance to what Yaakov now accepts as a Divine command via his mother, a prophetess.

So which is it - does she or doesn’t she? And does it make a difference in what Yaakov did if his was guided by a mother that loved him or by prophecy? Food for thought, at least.

Another comment on the question of Rivka’s prophecy. It is possible to distinguish between a prophet(ess) and one who “receives Rua’ch HaKodesh”. G-d might have communicated to her the "need” for Yaakov to receive the Bracha, and He might have told her about Eisav’s plans. That does not necessarily make her a prophetess, whose messages are for future generations. Many more than the 48 listed prophets were spoken to by HaShem, but only those who had a message for the generations make the list.