I farmed mines from Klunk quest in nulgathwar ...
After the Dage/Nulgath War quests went rare, it's almost impossible to get a large amount of Diamonds. I've always wanted Abyssal Priest of Nulgath, but it would take months on get enough diamonds with just Mana Golem/Supplies to Spin.
5th Upholder: Star Swords vs Navals
Hmm I spent maybe around 700-1000 diamonds on my armors and weapons idk