Diamond Ore

Diamond ore is generally considered to be one of the most valuable and elusive blocks in the game. It can be mined for a diamond gem using an iron or diamond pickaxe. Diamond ore can be obtained by the Silk Touch enchantment on a pickaxe.

Uses
Diamonds can be used to make shovels, pickaxes (diamond pickaxes can be used to mine obsidian), axes, swords, hoes, and armor of the highest quality. It is also a prerequisite ingredient in Jukeboxes, solid diamond blocks, and enchantment tables. If you want to mine and correctly gather the diamond, use either an iron or diamond pickaxe.

Smelting
Note: The only way to get the Diamond Ore block is to use a tool with the Silk Touch enchantment, or creative mode.

Prospecting
Diamond ore can be found in veins of 1-10 blocks (sometimes even more if multiple veins happen to spawn together, and down to 1 if the block that was supposed to be diamond ore is occupied by dungeon, ravine, stronghold, lake, lava pool, other ores, patches of dirt and gravel etc.) Diamond only appears in the bottom 17 layers of the map.
 * Diamond ore occurs in roughly 0.0846% of stone from levels 2-17.
 * There is an average of 3.097 diamond ore per chunk.
 * It is a good idea to dig around a diamond block before mining it to ensure that the gem won't fall into a cave, lava, etc. (This is especially necessary if you happened to stumble upon a lava lake nearby)
 * It is recommended to use a pickaxe with the fortune enchantment when mining diamond. This can yield up to 4 diamonds per ore block (with Fortune III).
 * There is an average of 1 vein of Diamond Ore per chunk.
 * There is no evidence that lava pools enhance chances of finding diamond. They merely spawn at about the same altitude. If you see lava, it doesn't necessarily mean there's diamond nearby, it only means you're in the bottom 16 layers of the world, the altitude where diamond also spawns.

A real case example of diamond ore distribution


For this example, a new world was created in Minecraft 1.2. The data from the save file was then extracted for 416,342 chunks, and the number of diamond ore blocks occuring at each layer was then counted. Although diamond starts to appear from level 15 downwards, it is pointless to mine on that level; you should instead focus on the layers with the highest concentration of diamond, between levels 5-12. Oddly, there is slightly less diamond ore in the middle of that range (around layer 9).

A possible strategy for diamond mining would be to build a branching mine on level 11, and another one on level 7 or 6, having mining operations on where the peaks of diamond concentration are, while also covering neighboring layers with high diamond concentration.

History
When diamond was first introduced in Indev 0.31 (January 29, 2010), it was called emerald.

Before Beta 1.6, Diamond was about 50% more rare in the north-east quadrant of the point (0,0) compared to the quadrant to the south-west. In Beta 1.6 Clay Blocks were more rare than diamond due to a glitch.

Diamond has become about 25% rarer as of Beta 1.8.

In snapshot 12w22a Diamond ore drops experience orbs.

Trivia

 * Diamond ore can be smelted into a diamond gem, although the only way to obtain the ore is with the silk touch enchantment. Mining it normally produces a diamond rather than the intact ore. However, it could be smelted even before the then-unobtainable Redstone and Lapis Lazuli ores could be smelted.
 * Diamond, like other ore, is easier to find in caves and empty lava pools, as this gives more surface area. But, diamond is more likely to be split by the caves or lava pools, yielding less ore.
 * In some vein formations, ores connect diagonally. Therefore it is recommended to mine around diamond ore. This also permits checking for lava.
 * Diamond ore, along with other ore, appear in the background on the achievement page.
 * Diamonds are considered to be the rarest item in the game. However, during Beta 1.6, Clay was actually rarer due to a bug. Likewise, in 1.0.0, End Portal Frames are purposefully rarer, but finding them is more controllable.
 * Once a slime-spawning chunk is found, creating a bigger cavern for them to spawn in is a good multipurpose way to look for diamond (when closer to bedrock) and other ores.
 * Diamond ore always occurs in groups of two or more, unless some of it was replaced with a cave, stronghold, or an abandoned mineshaft.
 * In 12w21a and 12w21b Emerald is considered more rare then Diamonds as it generates only in extreme hill biomes.