English: The Wulff construction gives the equilibrium shape of a crystal.
The red curve, denoted by ${\displaystyle \gamma }$, is the free energy of the surface as a function of direction (for each direction, the length of the red vectors is proportional to the free surface energy). Dark red radial vectors are passed from the origin to the ${\displaystyle \gamma }$ curve, intersecting it, and dark blue lines ${\displaystyle t}$ are drawn such that they are perpendicular to the radial vectors. The crystal shape is tangential to the ${\displaystyle t}$ lines (their inner envelope) and is indicated in blue.