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 gray Shades of gray Variations of gray or grey include achromatic grayscale shades, which lie exactly between white and black, and nearby colors with low colorfulness. A selection of a number of these various colors is shown below. Below is a chart showing the computer web color grays. An "achromatic gray" is a gray color in which the red, green, and blue codes are exactly equal. The web colors "gray", "gainsboro", "light gray", "dark gray", and "dim gray" are all achromatic colors. A "chromatic gray" is a gray color in which the red, green, and blue codes are not exactly equal,