Finally I have a scientific explanation for how women can tell the difference between the 8 billion shades of red available at the nail polish counter: they can see that part of the color spectrum better than men can:

The increased [genetic] variation enhances the ability to discriminate between colors in the red-orange spectrum, particularly among females, because they have two copies of the X chromosome

I wonder if this also somehow explains how women just know that you're wearing brown socks with your blue suit?