[1] If you dye your hair, you've likely noticed that all hair dyes have a system of numbers, and sometimes even letters signifying what shade is being used. There's no mystery to this code however, and you can use it to choose a shade of hair color and plan your own dye job properly. This is because the numbering system of dye gives you a lot of information. Most importantly, it tells you the hair color levels of different shades. What are hair dye codes? Every hair dye you will ever use has a code of some kind that specifies which shade it contains. This code is called the international color code (ICC), and acts as a universal guide for hair color manufacturers to label their products. The first number in the code describes the hair color level, whilst the second and third numbers are used to describe primary and secondary tones that are present in the hair color. Example - the 1.1 shade of Indola Profession blue black hair color The first number is used f