Extended Wulff constructions
Extended Wulff constructions refers to a number of different ways to model the structure of nanoparticles as well as larger mineral crystals. They can be used to understand the shape of gemstones and crystals with twins, and in other areas such as understanding both the shape and how nanoparticles play a role in the commercial production of chemicals using heterogeneous catalysts.
Source: Wikipedia — Extended Wulff constructions (CC BY-SA 4.0)