Here we have the common twist in nose stud often called a nose screw.  It comes in the option of 18g or 20g. It has a 2mm Simulated Diamond Bezel Set Stone.  
 
Specifications
 
Material: 316L Surgical Steel
Finish: Silver
Stone Size: 2 mm
Stone Type: Simulated Diamond
Stone Colour: Clear
Gauges Available:
                                    ~ 20g (1 mm)
                                   ~ 18g (0.8mm)