The Divination is an "item" used during the Cipher quest chain obtained from Kerrsh. It does not actually appear in the inventory, but rather causes a bar to appear on the screen. Once you get within a certain distance of the Facet you are hunting, the bar will begin to fill in with a teal color, which changes to red once the bar is half full. The bar will fill as you move closer to the Facet, and empty as you move away, similar to a "Hotter, Colder" game. At first, the bar will fill quickly, but as you get closer to your target it begins to fill more slowly. Once the bar is completely full, the Facet will spawn and you can kill it to complete the quest.
While doing these quests, this bar will not show if you do not have "Mission Progress" checked off inside your interface options.