The transformation in CIELAB from differences in the L*, a*, b* coordinates to those in lightness, chroma, and hue, Delta L*, Delta C-ab*, Delta(ab)*, can be approximated by a rotation in 3-space. Expressions for the error in the approximation of chroma and hike differences are developed. Significant errors are introduced if either the hue angle or chroma difference between reference and sample colors are large. A computed example illustrates the use of the analysis.