This paper presents a method to determine just-noticeable differences in multispectral color space. The basic idea is to find a meaningful connection between (u*, v*) chromaticity diagram and multispectral color space. The (u*, v*) chromaticity diagram is in focus for the reason that just-noticeable differences, which are Euclidean distances in (u*, v*) diagram, have about certain constant value. The visual equivalence of two multispectral vectors is examined based on a metric, which produces values linearly dependent on the Euclidean distance. The paper introduces a metric of that kind. The experiment was carried out on Munsell database measured by the University of Joensuu. The method presented can be used in quality control, image processing, and remote sensing to verify if multispectral colors are constant for the observer.