NCS stands for the Natural Color System. This is a color system developed by the Swedish Color Institute using color model based on opposite colors. The NCS system is presented in a Color Atlas containing 1950 color samples. NCS is widely used in various branches of industry to define the color of virtually any surface.

Shades in NCS are described by a combination of two of the six primary colors: white, black, red, yellow, green and blue, as a percentage between them, plus saturation and darkness of the color.

Colors according to the NCS standard are indicated in the form of a code with NCS prefix. In some cases a letter indicating the version of the standard can be added to the prefix:

NCS A XXYY-EZZI,
where A is the version of the NCS standard,
XX - darkness of color, %,
YY – saturation, %,
E, I - designation of primary colors,
ZZ is the percentage of the primary color I in the described color. The primary color E is determined as 100%-ZZ%.

Example: designation of Signal Blue RAL5005 according to the NCS standard would be NCS S 5248-B31G - version 2, 52% dark, 48% saturation, 69% blue, 31% green.

This method allows to uniquely identify any color. In addition, it is believed that NCS system, unlike RAL, allows a skilled specialist to intuitively conceive any particular color.