The Sage medal will be awarded for reaching certain level thresholds by a particular time (probably 1 December 2017 11:59 pm PST).

Niantic is holding a competition to design the medal. If the medal follows the pattern of the Vanguard and Luminary medals, the level thresholds will be as shown in the table below.

Tier Level
Bronze 3
Silver 9
Gold 13
Platinum 15
Onyx 16