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Because these definitions of saturation – in which very dark ( in both models ) or very light ( in HSL ) near-neutral colors, for instance or are considered fully saturated – conflict with the intuitive notion of color purity, often a conic or bi-conic solid is drawn instead (), with what this article calls chroma as its radial dimension, instead of saturation.

Confusingly, such diagrams usually label this radial dimension " saturation ", blurring or erasing the distinction between saturation and chroma.

As described below, computing chroma is a helpful step in the derivation of each model.

Because such an intermediate model – with dimensions hue, chroma, and HSV value or HSL lightness – takes the shape of a cone or bicone, HSV is often called the " hexcone model " while HSL is often called the " bi-hexcone model " (