According to wisegeek.com: "There are about 450 to 500 medieval Black Madonna's in Europe, with at least 180 in France." Apparently, these black Madonna's were created back in medieval times from the 12th through the 15th centuries, to which one standard explanation of this phenomenon attests that because the Madonna was situated near to the burning of candles for so long, that thereby the soot generated darken the Madonna over the years. Perhaps this explanation would hold more water if there weren't so many Madonna's all over Europe with the same dark characteristics, but because this is so, this indicates strongly that the Madonna as originally conceived was purposely made dark. This does then lead to the question, but why?
To answer the question in part is to recognize that it is the victors that write the history, and our Western Civilization has been conceptualized in the last five hundred years or so, as primarily Caucasian, and in particular, as light skin, so that in this culture, it makes sense to visualize the Madonna as having the same characteristics in color, even though Jesus, Joseph, the Virgin Mary, are from a prototypical middle eastern heritage which would imply a more swarthy look, as opposed to something that is porcelain white. All of this is because it is the norm to want to project upon our God, his mystics, and his prophets that in the physical, that they look remarkably similar to us. However, again, why the black Madonna, in Europe no less?
Perhaps the black Madonna originated in reference to the fact that darker soil is considered to be the richest and most organic of soils, so her darkness signifies that she is the epitome of one of our own. Her darkness heralds that from this good earth, God himself can re-birth Himself so as to redeem us from our missteps and frailties. That, in fact, Our Lady, is universal, and applies to all cultures, to all people, and thereby to everyone. It is of vital importance that her presence strengthens us in our belief that as Our Cosmic Lady, that her special annunciation and that her acceptance of such, was made as demonstrative proof that man is not forsaken, but loved.
Our black Madonna makes it easier to understand that she too, is the suffering servant of God, for that her own Son, from her womb, was crucified. Yet, her dark complexion helps us to more readily recognize that rather than her appearance to us coming across as too purified, too refined, and lacking in substance, that she is indeed one of us, and the personification of what we can aspire to be as she is our devoted and nurturing mother.
In todays color conscious world, we may seem a bit befuddled by the whole phenomena of a black Madonna, but color as a classification, for the separation of a given people, as a dividing line for class distinction, is of recent heritage, as history has typically divided man by classification of birth, faith, and his associated social status as compare to the pigmentation of a person's skin. Our Divine Lady knows no class distinction, nor faith, nor social status, nor color, only that we all are one in God.