Emberguard
Legend
What do you see that makes it an obvious diamond mine city?
First 6 hrs of the world being open = 12 wishing wells from the carnival event, some victory towers, some hall of fames, two shrines of inspiration, 2 shrines of awe in Iron age with Observatory and oracle.
Currently on global chat: people asking if he's ever aided or visited anyones taverns.
He founded the first guild for Rugnir and consequently people flocked because it had a player with the highest score in the game as its leader.
Now they're late middle ages and still have those wishing wells set up, 5 halls of fame all upgraded from Iron age to High middle age, has 8 Iron Age shrines of knowledge, 4 Shrines of awe (high middle) and 5 Lvl 7 Carnival Bridge, 3 in late middle age, 2 in high (he was no later then early middle when the event ended)
So either he's dumping ton of cash on rugnir, or he has a diamond farm elsewhere