Diamonds will also be used to shop for ornamental skins for castles or march effortlessly
https://delta-wiki.win/index.php/King_of_Avalon_Top_Up_Savings:_Unlocking_Discounts_on_Diamond_Packs_22723
Diamonds will probably be used to shop for ornamental skins for castles or march outcomes, letting you customize your kingdom’s appearance in flavor.