These are used in the Eron's Jewelry quest and requires you to make 3 Shadow boxes that each use a Gem Covered box.
They drop in Loping Plains, Dragonscale Hills and Hills of Shade. However, they are lore, so you can either loot one from each zone OR make a shadowbox one at a time which uses up the Gem Covered Box and allows you to re-loot another one from the same zone.
As I understand it, they each identify as something different.
Edited, Jan 10th 2023 5:26am by Bilderov