It is permissible to wear nail polish provided that the ingredients are not of haraam substances. The problem with?nail polish lies in it being?impermeable (liquid cannot pass through) thus making Wudhu or Ghusl over it invalid. For Wudhu or Ghusl to be valid water has to reach the nails. If one is wearing nail-polish then water will not reach the nails and Wudhu or Ghusl will be invalid. Before making Wudhu or Ghusl every last dot of nail polish will have to be removed thoroughly and totally. Doing this is very difficult and mistakes will happen. Therefore, it is highly recommended that one does not wear nail-polish as it is not?worth jeopardizing your Wudhu, Ghusl, Salaat, and Ibadat over. Rather color one's hands and nails with Mehndi/Henna as this is permeable and the Wudhu/Ghusl over it will be valid.
