Cockburn developed the different methods in the family of methodologies to suit teams of different sizes which need different strategies to solve diverse problems.
The Crystal family of methodologies use different colours to denote the “weight” of which methodology to use. If a project were a small one a methodology such as Crystal Clear, Crystal Orange or Crystal Yellow may be used or if the project was a mission-critical one where human life could be endangered then the methods Crystal Diamond or Crystal Sapphire would be used.