Different large magnitude colour-difference (LCD) data sets were accumulated. A uniform colour space based upon modification of CIELAB was developed to fit each data set. These spaces were then compared to reveal the differences between the different data sets. The results showed that all LCD data sets have fairly similar characteristics to each other except for the Munsell data due to the incorrect balance between the lightness and chromatic data within the latter data set. The present results show that a one unit of Munsell Value appears larger than one unit of Munsell Chroma by a factor of 1.25.