Diamond

Diamonds are a rare mineral obtained from diamond ore or loot chests. They are mainly used to craft high-tier tools and armor, and the enchantment table.

Mining
Diamond ore mined using an iron pickaxe or stronger drops a single diamond. If mined by any other tool, it drops nothing. If the pickaxe is enchanted with Fortune, it can drop an extra diamond per level of Fortune, allowing for a maximum of 4 with Fortune III. If the ore is mined using a pickaxe enchanted with Silk Touch, it drops an ore block rather than a diamond. The ore is found at level 18 or lower, most commonly between 5 and 12. If you dig in a straight line in these levels, you will most likely run into diamonds.

Usage
Diamonds are mainly used to craft high-tier armor and equipment, which in turn are also used in crafting netherite armor and equipment.

Trading
$$, expert-level armorer, toolsmith, and weaponsmith villagers buy one diamond for an emerald as part of their trades.

$$, journeyman-level armorer villagers have a 40% chance of offering to buy one diamond for one emerald. Expert-level toolsmith villagers have $2/3$ chance of offering to buy one diamond for one emerald. Expert-level weaponsmith villagers always offer to buy one diamond for one emerald.

Repairing
Diamonds are the repair items for the diamond tier and armor material, and thus can be used to repair the following items in an anvil:

Beacons
Diamonds can be used to select powers from a beacon. The player must select one of the available powers then insert a diamond into the item slot.

A diamond can be substituted for an iron ingot, a gold ingot, an emerald or a netherite ingot

Trivia

 * In real life, diamond is commonly used for industrial purposes, generally as diamond-tipped drill bits and saw blades. They are usually used for cutting stone and other hard materials. Diamonds used for this purpose are typically not of gemstone quality.