If you have taken all courses that qualify for a degree, your diploma will be sent to you automatically after you have passed the oral examination.
However, you may apply to postpone your diploma for maximum 2 semesters after you have finished your degree, in order to re-take exams.
Deadline: 20 May (for students finishing their degree spring 2017)
Read more about this and apply here: http://www.sv.uio.no/english/studies/master/econ/postpone-diploma.html