Measuring curved / irregular parts and getting bad color readings.
Before mandating any Quality Control, or Color Measurement Program some basic fundamental steps must be in place such as repeatable and re-producible sample measurements
This customer is measuring curved samples that vary in size, shape and diameter. The non-uniform or curved surface of the samples is causing large amounts of light leakage causing inconsistent measurements.
Suggested measuring on the flat part of the sample, and/or using standardizes a sample holder.