Human hair color account for all possible shades of brown, blond, or red (for example, platinum blond versus dark blond/light brown), nor does it explain why hair color sometimes darkens as a person ages. Several gene pairs control the light versus dark hair color in a cumulative effect. A person's genotype for a multifactorial trait can interact with the environment to produce varying phenotypes (see quantitative trait locus). Natural hair color can be brown, blond, black, red, or white; all natural hair colors including grey, white and lightest blond, are shades of brown. The Fischer–Saller scale, named after Eugen Fischer and , is
Shades of azure lapis lazuli is displayed at left. "Lapis Lazuli" is a color that is a representation of the most common color of lapis lazuli. The traditional color called royal blue is a dark shade of azure. Shades of azure Azure ( ) is a variation of blue that is often described as the color of the sky on a clear day. On the , "azure" (hexadecimal #007FFF) is defined as the color at 210 degrees, i.e., the hue halfway between blue and cyan. In the RGB color model, used to create all the colors on a television or computer screen, azure