We always wore black while I was a collegian, but sisters were free to choose the style of outfit they wore (just as long as it was badge attire). We wore badges, and I always wore a pearl necklace that a chapter sister made for me.
I always thought it looked really classy, as you can never go wrong with a classic black dress.
Besides, we had pink punch at preference, and so if we spilled or splashed a little onto a black dress, it wouldn't be as bad as if it had been a white dress.
Sigma Love and Mine,
Laura