Depth

For a lipstick, depth comes from the shade’s measured lightness, the L* value in the CIELAB colour space. The encyclopedia groups shades into five bands: very light, light, medium, medium-deep and deep. The cut-off values are listed on the methodology page. Depth is separate from undertone: a pale pink and a deep berry can both be cool.

For skin, depth is usually described as fair, light, medium, tan or deep, and the skin-depth hubs on this site use those five names.

Depth matters because it sets contrast. A shade much deeper than the skin reads as bold and defined; a shade close to the skin’s own depth reads as soft. This is why the same nude can look natural on one person and pale or muddy on another, and why the site lists light shades for fair, light and medium skin, deep shades for medium, tan and deep skin, and medium shades for everyone.