Quality is a reflection of meeting all expectations. But how do we agree on this? As Hannah Arendt states, "truth only exists in pairs", and suppliers and customers need to align on specifications. Pearlescent pigments distinguish themselves by an angular-dependent colour characteristic. Their quality is traditionally assessed visually by experts in comparison to a defined standard reference under defined light conditions. Multi-angle spectrophotometers have been developed for the purpose of measuring instrumental data, enabling quality to be assessed independently from visual and individual evaluation. However, the strength of visual evaluation is a holistic impression under all angles. It is fast ...