From Minecraft Wiki
Diamond may refer to:
Blocks and items
Diamond - The item obtained from mining diamond ore, used to craft the most effective tools, weapons and armor in Minecraft.
Diamond Ore - A very rare and desirable ore found near the bedrock layer deep underground.
Block of Diamond - A block crafted from 9 diamond gems. It can be used for compact diamond storage or for decoration.
Tools, weapons, and armor
Diamond Horse Armor