Where to find Faceted Rock Gem
Dig archaeological spots in the Deep Earth on mine floors 41–59. The Stoneturner perk can also make it drop from rocks there.
What to do with it
Donate one to the Deep Earth artifact set and keep one for Breaking the Fire Seal.
What is confirmed and what is not
It is an artifact despite its name; mining ordinary gem nodes is not the normal route.
Primary sources
Checked against these public pages. Official sources define confirmed features and status; community sources are labelled as such and used for game data that the developer does not publish directly.