Many users assume that since they do a daily calibration on their instrument, their readings are correct. And if they are correct, then they must match every else's. That's not usually the case. Spectrophotometers from different suppliers may read color differently. Even with the same model from the same supplier, significant differences can be found depending on the age of the instrument and how well it is maintained.
Color QC and Matching Blog
One of the more frequent questions we hear from suppliers is: What should my color tolerances be? The simple answer equates to what the client will accept in color variation in all directions of color space versus the color standard the supplier needs to match. The importance of the client providing representative color standards will be the subject of a future blog.