Porter's diamond is a model used as part fo the strategic analysis stage of the strategic planning process.
Porter tried to answer the following questions:
Why does a nation become the home base for successful international competitors in an industry? Germany is renowned for car manufacture; Japan is prominent in consumer electronics.
Why are firms based in a particular nation able to create and sustain competitive advantage against the world's best competitors in a particular field?
Why is one country often the home of so many of an industry's world leaders?
Porter called the answers to these questions the determinants of national competitive advantage. He suggested that there are four main factors which determine national competitive advantage and expressed them in the form of a diamond.
Porter's Diamond