Chameleon turquoise, and purple. Chameleon skin has a superficial layer which contains pigments, and under the layer are cells with guanine crystals. Chameleons change colour by changing the space between the guanine crystals, which changes the wavelength of light reflected off the crystals which changes the colour of the skin. Colour change in chameleons has functions in camouflage, but most commonly in social signaling and in reactions to temperature and other conditions. The relative importance of these functions varies with the circumstances, as well as the species. Colour change signals a chameleon's physiological condition and intentions to other chameleons. Chameleons tend
RAL colour standard relates to the shade of the colour: This collection, which follows the naming of RAL Classic, was invented in 1961. It is nowadays made up of ten colours (RAL 1039-F9 Sand beige, RAL 1040-F9 Clay beige, RAL 6031-F9 Bronze green, RAL 6040-F9-Light olive, RAL 7050-F9 Camouflage grey, RAL 8027-F9 Leather brown, RAL 8031-F9 Sand brown, RAL 9021-F9 Tar black and RAL 6031-HR Bronze green for non-camouflage applications), used by the "Bundeswehr" for military camouflage coating. In 1993 a new colour matching system was introduced, tailored to the needs of architects, designers and advertisers. It started with 1,688 colours and was