There were three graduate colleges in Padua, defined as being “sacred” because the popes had given them the privilege of granting doctorates: the graduate college of jurists, which presumably existed even before the university was established (1222), the graduate college of doctors and artists, which was probably created in 1250, and the graduate college of theologists, which was established at the same time as, or immediately after, the creation of the theology department.
Each college had their own charter and their own seal featuring the image of their respective pro-rector: Madonna with the Child for the jurists, St. Luke with the symbolic ox for the artists and St. Jerome on his knees for the theologists.
The college of jurists and the college of doctors and artists were made up of local graduates who had or hadn’t studied at the university and of ‘foreign’ graduates who had studied in Padua. There were initially 12 members, then 20 and, lastly, with regard to the jurists, an unlimited number. 
Their main role was to grant doctorates. Scholars in the graduate colleges were assessed who had completed their studies and who, according to the ancient charters, had completed a total of six years of studies for canon and civil law, five years for liberal arts and at least three for medicine.
A doctorate could be granted to foreign students after only a few years’ attendance as long as they could prove that they had studied at other universities or that they had sufficient scientific knowledge and experience.
In order to be granted a doctorate, a scholar, with the help of his promotores, had to take two exams in Latin: one private exam, which was more scientific, and one public exam, which was less complex but more serious. The first exam granted scholars the licence to allow them to receive the doctorate and to practise the profession, whereas the second exam granted them the doctorate to enable them to teach. Scholars who discussed their assigned topics well enough were proclaimed “graduates” and received their doctoral certificates.