What is the past and current halacha for women wearing red clothing or red nail polish? also please provide sources for the older prohibition and if there is no prohibition today then please also provide a source thank you
It goes by local custom. Some see a problem hinted in a story in the Talmud (Brachot 20a) and in some places, that was considered a clearly gentile color (Maharik in Beit Yosef Y.D. 178), but many leading poskim today say that this no longer applies (including R. Yitzchak Elchanan Spector, Darkei Tshuva 178, 16), and so hold most mainstream poskim. Accordingly, many halachically modest women wear red nail-polish, as well as red clothing, but even if some don't, don't make an issue if your wife wants to... The main thing is that one shouldn't wear any “loud” shade of color which is designed to call attention.