The location I was talking about was in Stone's headquarters. There's a room to the left that constantly spawns walking armors until you overload it with the jewels you find around it. This jewel was up in one of the arena shafts for some reason. I thought it could be one of the big metal doors in the arena but it's not. I also researched the Stone's Headquarters and none of those machines reacted to the item. I would search more, but empty fortress's are boring.
