Cacao nibs can vary in colour, and the appearance you described is generally considered natural. Cacao nibs are made from crushed and roasted cacao beans, ranging from light brown to dark brown. Some white or lighter-coloured pieces can also be natural and are often a result of variations in the roasting process or the specific cacao beans used. It's not unusual to find a mix of different shades in a batch of cacao nibs. These colour variations do not typically indicate any quality or safety concerns; they are just part of the natural characteristics of cacao nibs.