In this paper a new HS chromaticity diagram for 10-degree observer with more linear colour distribution is presented. Both, the spectral locus and curve of purple colours generate unity circle -the HS diagram. By using the CIE lightness L as the third dimension, the Lrnn colour space is generated. This new colour space is embedded into cylinder radius of 100 (it stands for chroma) and height of 100 (it stands for lightness). If n is plotted against m the points in resulting Lmn-space are not uniquely related to chromaticity because their position depends on the value of L. The colours of all object-colour stimuli fall within this cylinder boundary. The spectrum locus of the monochromatic stimuli is generally well outside the boundary of object-colour stimuli.