so no wudu isnt valid if u perform it with nail polish cus water cant reach the nails which r part of ur hand and hands r one of those parts that r fard to be washe while performing wudu
so nail polish has to go b4 wudu
well its clearer water cant reach nails actually but it does reaches its surface, any dust or particles cleared..
although i brought in exception but you are going by the word and not the purpose.