Islam generally encourages Muslims to appear neat, tidy and well groomed; this applies equally to males and females. Greater emphasis in this matter, however, has been placed on married couples more than others; Ibn `Abbas (may Allah be pleased with them) said, “I prepare myself for my wife even as she prepares herself for me!” The reason for this is not hard to comprehend as such appearance may go a long way in contributing towards martial stability and fulfilment as the spouses are supposed to serve as garments of protection for one another.
as for nail polish as a product, it is not haram (prohibited). However, there are two issues you should know about nail polish.
1. A woman can pray with nail polish; but when she takes her ablution, she should have it off, otherwise, both her ablution and her Prayers will not be valid. Then, if she removes the nail polish, takes her ablution, and then puts the nail polish back, then she can pray with it.
2. Nail polish is an ornament. Therefore, like all other ornaments, it cannot be worn in public in the presence of the opposite sex (men). A woman can only have it in front of her husband, children, and all other women or men who are her mahrams (those she can never marry, like her father, uncle, etc.). If a woman really wants to put nail polish and go out, then she should cover her hands with gloves.”