The coloured squares may all look the same to you but I can assure you they are not.
In my computer aided design class we were given 5 swatches of coloured fabrics and needed to create the same colour on illustrator with slight variation by adjusting the CMYK (Cyan, Magenta, Yellow, Key (Black) ) percentages.
Then we had to print our colours and see whether the colour of the swatch matched the colour of the print out.
In the photo is my first attempt. I got close but not close enough.