A stent assembly comprises a rotatable sheath and a stent. The assembly is crimped or reduced in diameter prior to loading onto a catheter by one or more crimping apparatuses. One crimping apparatus comprises a blade having a stepped configuration. A mandrel may be used to support the assembly during crimping. The mandrel may have an expandable region. A protective sheath may be used to protect the stent during crimping and to redirect the crimping forces to desired locations about the assembly.