Examples disclosed herein relate to creating a surface identifier using a shape memory material. In one implementation, a processor determines a first property value of the surface identifier associated with a first phase and a second property value of the surface identifier associated with a second phase. A manufacturing device may create a surface identifier using a shape memory material. In one implementation, the surface identifier is created in a manner that causes the surface identifier to exhibit the first property value when the shape memory material is in a first phase and to exhibit the second property value when the shape memory material is in a second phase.