On The Ancient World, Diamond gear crafting recipes are disabled as a means of extending the life of the server.

In modern Minecraft, an experienced player can get a full set of diamond armor within hours just by mining. By disabling the recipes, we stay in the Iron Age a lot longer. This makes the early-game struggle last days or weeks instead of hours, which is more rewarding.

Diamond gear can still be found in the world in chests of old abandoned bases, making exploration much more meaningful. Diamond gear can also be acquired as a reward from events.