I am thinking about getting my sisters each a pair of pearl earrings, probably drop pearls, as these are a little more casual, but I don' know what color. Should I go with a classic white, or would a light grey be a less formal (i.e., more "wearable") alternative? One is about to turn 25, the other is 27, so they are still fairly young. I want to give them something classic that they can wear forever, but still trendy enough to look their age. Suggestions?