Question: Is there any sin involved in a woman wearing nail polish? What should she do when doing wudoo?

Answer:

Praise be to Allaah.

We do not know of any ruling on that, but it is better not to use it, because there is no need for it, and because it may prevent the water reaching the skin when doing wudoo’. In brief, it is better not to use it, and to be content with henna, because that which the earliest Muslim women used is better. If a woman does use it, then she has to remove it when doing wudoo’, because – as we said – it prevents the water from reaching the skin. And Allaah is the Source of strength.

Shaykh ‘Abd-Alazeez ibn Baaz