I heard once that single women were supposed to wear white veils and married women and widows were supposed to wear black veils. I am not sure, though. I may have heard wrong.

My mother taught me to wear a white mantilla as a virgin and varied colours once married.

A young lady may wear whatever color best complements her.  I remember back before the chapel veil was discarded the only time I saw white was when someone forgot her veil and pinned a klenex on her head (and, back then, all klenex tissues were white).

However, in many people's opinion, white is most appropriate for young girls and unmarried young women, while black and other colored veils are best for married women.  My wife and girls mostly wear the small black veils, though they also have pink veils (that they wear twice a year) and blue veils (that they often wear on or near feasts of our Lady).  

They also have some headscarves that were given to us from someone stationed with the U.S. Army in Afghanistan and we've found that if you don't wear it like you see Muslims wearing them they don't look the least like Muslim head-dress.  These are in a variety of colors and we have several so that they can wear one, if they like, that matches their blouse or dress.  Often, though, they wear a veil and use the headscarves as shawls when it is chilly.

My eldest daughter wore, for a time, a very nice, modest dress hat (it was mostly white) until she decided to enter the convent at Mount St. Michael's.  There are a couple of young ladies at one of the chapels my family attends who always wear a hat.

Bottom line:  Women don't have to limit themselves to white or black veils and they don't even have to limit themselves to veils.  They are to cover their heads, but there are many ways to do so that give glory to God.

I don't think there are any hard fast rules about it as far as I know. I really appreciate symbolism, so I wear white. If I were to marry or enter the convent I would switch to black.

TKGS and others have given wonderful suggestions about wearing colored veils. I've been wanting to either buy or make a few veils for different liturgical times. Or there are hats. I am 100 percent partial to veils, though, as that's what we see Our Lady in.

Does either color indicated a woman's marital status? I want to buy my wife a chapel veil for the birth of our first child. White? Black? Does it matter?

The Blessed Mother of God seems to be depicted as wearing a blue head covering a lot.  Maybe get your wife a blue chapel veil in honor of the Blessed Mary :)

Just don't use toilet paper and watch what your children use.  Once when I was a child I was late getting ready for Mass, couldn't find my mantilla or a Kleenex so I grabbed some toilet paper as I rushed for the door.  My mother didn't notice until we were well into the Mass when she yanked it off my head and handed me a Kleenex!  At least we were sitting in the back of the church!