A cartridge for piercing in a body part for positioning a piece of body jewelry comprises a bar and a locking mechanism. The cartridge comprises two sections which are articulated to each other along a pivot and which are movable between a closed state and an open state by being pivoted on said pivot, and a locking member for locking the sections in their closed state. In their closed state, the sections define a space for receiving said piece of body jewelry, an opening and a guiding surface. The bar of the piece of body jewelry is arranged to be pushed out of the opening while the bar is being guided by said opening and while the locking means of the piece of body jewelry is being guided by said guiding surface. In their open state, the sections allow the piece of body jewelry to be released from the cartridge after completed positioning.