Diamonds are some of the most sought-after items in Minecraft, due to their use in crafting the strongest tools, weapons, and armor available in the game. Diamonds are also some of the rarest items in Minecraft, found only in the deepest levels of rock. This makes diamonds extremely difficult to find and severely limits players' supplies of diamonds. This tutorial is intended to help players who want to obtain, maintain, and expand their diamond supply.
You must have an iron pickaxe (or stronger) in order to mine diamonds. A water bucket, an iron sword, iron armor, and other usual caving supplies are also suggested.
 Finding Diamonds
Diamonds can be obtained from diamond ore, an extremely rare block that occurs in 0.0846% of stone from levels 2-16. Typically diamond is found near dirt around layer 9. There are two methods for locating ore: by caving or by mining. Either way, you'll need an iron pickaxe to mine the diamonds (also any gold, emerald or redstone you come across). Although it may be tempting to use stone tools in order to attempt to save the durability of your iron tools, stone should only be used when iron is in very short supply. This is due to the fact that iron is relatively common and has a greater mining speed and durability than stone. Consider that because iron tools mine faster, it is possible to mine a certain amount of iron in addition to recovering lost iron in the same time it takes for stone to mine just the extra iron meaning that in the long run "conserving iron" actually wastes it. You'll also want a supply of torches and wood for more (you'll likely find plenty of coal along the way). If you're caving, you'll want the usual supplies for that, notably armor and weapons. Diamonds can sometimes be found in Village chests.
 By Caving
Caving is less resource-expensive (except in torches) than mining, but is more dangerous and time-consuming, since it requires you to explore a multitude of dark, monster-filled caves. To locate diamond ore by caving, simply explore any caves you find (either by locating surface entrances or digging) and work your way downward until you're below level 15 (the debug screen will help you check your depth). Ravines and shafts can provide shortcuts to the depths—creating a waterfall can help you get down (and back up) safely. Finding subterranean lava pools is a good hint that you're in the right depth range, but those are actually not the best place to find them—besides the hazard of lava, they can replace part of the ore body, leaving you with fewer diamonds to mine. (It's actually better to start mining whole stone, once you've established that you're at the right depth.) If you do see diamond ore veins exposed near a lava pool, use a water bucket to convert the surface of the pool into obsidian or cobblestone... then leave the area flooded while you mine. That way, if there's more lava under the diamond ore, the water will quench it before the lava can destroy your newly mined diamond(s). If you don't see diamonds immediately, don't give up - diamonds aren't considered rare for nothing. Search for more caves at similar levels, or switch to the next method: mining or searching for village chests.
 By Mining
Mining is safer and more reliable than caving, but consumes more tool-crafting resources. It also generates a lot of spare cobblestone, although in some cases this may be viewed as a downside rather than a benefit.
To create a diamond mine, first get down to the diamond layers. Besides following existing caves, you can just dig a vertical shaft, quarry, or staircase down to the diamond-containing layers (as you do this, remember the cardinal rule: don't dig the block you're standing on!). Most players prefer level 11, because that puts the "lava flood" at foot level. Deeper tunnels are likely to expose lava at head level or from above, but at level 11, lava will probably be exposed in the floor. This may block further progress, but probably won't flood down the tunnel! Once at your chosen level, begin branch-mining or mining long, level hallways two blocks high and one block wide. Sooner or later (often later) your mining will expose a diamond ore vein.
It's likely your mine will intersect several caves. Since any cave you locate while mining for diamonds is, by definition, at the right level for diamonds, it's a good idea to explore (and light) the cave before proceeding with your mine. Sometimes if you cover a lava pool with Glass, There is diamond ore under it (Use This In Rare Occasions!) Ice works also, but it melts quickly.
Video tutorial of "PinWheel" Mining Very easy way of Mining to get diamonds
 By Chunk Mining
This is a method of mining that takes advantage of how diamonds are spawned in Minecraft. In order to fully understand it, one has to understand the basic terrain generation mechanism of Minecraft.
Minecraft is generated in pieces of terrain called "chunks" which are 16 x 16 blocks horizontally and all the way from bedrock to sky (256 blocks) vertically. Veins of minerals are generated based on these chunks. The key here is that rather than diamond generating totally randomly, almost exactly one vein of diamond is generated in every chunk. (See below for details)*
This has two implications which make chunk mining equal to or superior to all other mining methods:
1: If you mine long enough in a chunk, there is a 97% chance to eventually find diamond.*
2: If you find diamond, then you know that there is no other diamond in the chunk and don't need to mine there anymore.
There is another two facts which make chunk mining for diamonds even better:
3: If all the blocks are broken in layers 10 and 11, then that means layers 9 (floor) to 12 (ceiling) are exposed. On average, 47% of diamond will be revealed. (Note that because of the fact that diamonds generate in veins and not stray blocks, this is closer to 60%)
4: Then if all the blocks are broken in layers 7 and 8, then layers 6 to 12 are exposed. On average 70% of diamond will be revealed. (Note that because of the above, this is closer to 85%)
With these ideas in mind, the power of this method of mining becomes very obvious. This is the most efficient way to go about this. You will have to use F3 to find the layer you are looking for and calculate the chunk borders. In Minecraft, coordinates are not dots, but lines. This makes things a little more confusing if this isn't something you understand. This means that the middle of a block is halfway between two coordinates.
Step 1: Dig down to level 10. This means that F3 will display "feet 10.00 eyes 11.62". It also means that if you keep mining your feet will walk through subterranean lava lakes.
Step 2: Dig forward to the nearest line divisible by 16, this means that F3 will display something like 159.566 when you go to the very edge of the block. After that, dig the other way so that the ends are nearest multiples of 16. This means each one will be something like 160 and 144. All the blocks in between these two lines or green boxes are a chunk. It should be 16 blocks. Do the same for the z coordinate using the F3 method. Even if you find diamonds during this, you should keep mining, because it is very important to have an origin chunk to discourage mistakes later on. Place torches or glowstone on the edge of every chunk. It won't be enough to light up the whole area, but it will show the chunk borders which can be hard to mentally keep track of.
Step 3: In a perfect world you will have a square tunnel 16 x 16 with a 14 x 2 x 14 block of stone in the middle. However this probably won't be the case on the first chunk.
Step 4: To help avoid confusion later on, mine out layers 10 and 11 on the origin chunk you start on. You don't want to find the diamonds on the origin chunk, you just want to set up a measuring tape to speed things up later on.
Step 5: By now you should have a 16 x 2 x 16 area of air that is the defining area of a chunk. Simply pick an adjacent chunk and dig in the corner.
Step 6: Dig the borders of the chunk and make torches at each edge. This means that if the chunks are being defined correctly, torches will be placed directly adjacent to each other. At the end of this step, you should have an empty 16 x 16 room and a 16 x 16 border next to it which has a 14 x 2 x 14 area of stone in the middle of it.
Step 7: Now dig tunnels through the 14 x 2 x 14 block, skipping every 3 blocks. This means that each edge (the wall) should be 3 blocks of stone, then tunnel. Three blocks of stone, then tunnel. Because chunks are 16 blocks long there will be an anomaly at the end. There should be 3 stone, 3 stone, 3 stone, then 2 stone.
Step 8: Do the same thing but along the other axis. You should now have a series of 3 x 2 x 3 and 3 x 2 x 2 blocks of stone.
Step 9: Go to the corner of the chunk and dig down 4 blocks. Repeat step 6 - 8 on layers 6 and 7. If you are doing this right then no bedrock should be visible in this level.
There is a 70% chance to have found a vein of diamond by step 9. If you haven't, there are a few reasons why:
1: The diamond spawned under bedrock or very high.
2: The diamond was overwritten by gravel or dirt.***
3: The diamond was overwritten by a piece of cave.***
No matter what it is, it isn't worth your time to go on if you haven't found any diamonds by step 9.
Remember that at any time between steps 6 and 9 you can find diamonds. Most diamonds are found during step 7. Once you find diamonds then stop. No other diamonds can be found in that chunk. Repeat step 5 - 9 once you find the diamonds in a chunk. You can find a vein of diamond in 10 minutes easily. Think about it, that's 25 to 30 diamonds an hour, guaranteed. Branch mining requires a significant amount of luck, but this method requires hardly any luck. You will find exactly the same amount of diamonds almost every time.
Lastly, there are a few other advantages to this method:
1: Most other mining methods will end up creating hundreds of blocks that you can take home. With this method, you will possibly find all of the diamonds right below your base (of which, there are hundreds just within 80 blocks of you). This means that farms and furnaces will keep functioning while you are mining, which isn't true with traditional branch mining or cave mining.
2: This method does not rely on luck nearly as much as branch mining. You will typically always find diamonds somewhere within the chunk. You don't have to stop at step 9 if you don't want to. Although in practice it is inefficient, you will probably find diamonds.*
3: There is really no time wasted in walking back to your base. Although if you find stacks of diamonds, you will only have to typically walk 30 - 50 blocks back to your main stairwell.
4: This method will keep you from dealing with caves as much as possible. This is highly recommended for people who don't like to deal with caves, because it is possible to find a whole stack of diamonds before a cave is finally intercepted.
 Video tutorial
This video is going to show you a very popular way to find the diamonds. The method is called "Branch mining".
 Mining Diamonds
Once you find a block or vein of diamond ore, you'll need to mine it to get the diamond gem it contains. Before you do this, though, make sure the area is safe: after all, you don't want to lose any diamonds!
First, if you've located the diamond ore by caving, light up or block off any nearby dark areas so you won't get blown up or shot while attempting to mine. Next, dig away all blocks directly adjacent to the vein, both to expose the whole vein and to make sure the diamonds won't drop into lava and burn; a very effective method of preventing anything from dropping into lava is: holding the "shift"(crouch) key and "W"(forward) key, while mining your resource. This will both prevent you and your precious diamonds from falling into possible lava below. If you encounter any lava, get rid of it before you mine the blocks.
Now that it's safe to mine, use an iron or diamond pickaxe to break the blocks. The blocks will drop one gem each, unless your pickaxe is enchanted with the Fortune enchantment (Fortune III, the highest level, will make ore drop as many as four diamonds, and on average doubles the yield of a diamond vein). Remember to dig around diamond veins, as diamonds can form diagonally in the same vein.
Now that you have diamonds, it's best to proceed directly to a safe place to stash them in a chest; this could be your home base or a secure mining outpost. Be careful to make the chest secure from attacks by creepers, or your precious new-found wealth could go up in smoke.
 Using Your Diamonds
Now that you have diamonds, you can begin crafting some of the best items the game has to offer.
 Diamond Tools
Diamonds can be used to make Shovels, Pickaxes, Axes, and Hoes that work faster (gold mines faster but is really weak) and lasts significantly longer than any other tools. Most players use their first three diamonds to make a diamond pickaxe, the only tool in the game that can harvest Obsidian blocks (Although a Diamond Hoe does last longer than any other hoe, it grants no speed boost and is generally considered a waste of diamonds.)
 Diamond Weapons and Armor
Diamond swords deal the most damage of any sword - eight points - and diamond armor protects the wearer better than any other form of armor. As with diamond tools, they also last longer than swords and armor made from lower-quality materials.
 Other Diamond Items
Diamonds are also used to make Jukeboxes, decorative diamond blocks, and, most importantly, Enchantment Tables, which allow players to convert Experience into valuable tool-improving enchantments. They can also be used as the ore to power a Beacon, but this is unnecessarily expensive and it is recommended to use emerald or iron blocks. If you are playing the Pocket Edition, you can use two diamonds to craft a Nether Reactor Core.
 Maintaining and Expanding Your Supply
Once you've realized how useful your first diamonds are, you'll probably want more. To this end, you'll need to continue mining. If you want to become truly diamond-rich, though, you'll need to do a few other things first.
 Getting a Fortune III Pickaxe
You'll want to mine with the Fortune Enchantment on your pickaxe, preferably level III, for your next diamond vein, to significantly improve the amount of diamonds you get. Alas, this is not something you can rely on, but you can try.
Enchanting is somewhat complex, but here is how to bootstrap the equipment needed: You need to start with at least 5 diamonds: The first three will go for a diamond pickaxe. This lets you mine obsidian, and you need four blocks. That plus the other two diamonds will go for an Enchantment Table, but first you need to make a book. In fact, you'll need to make a lot of books, but you can start with one to get the table made.
For the books, you will need leather (from cows), and paper, from sugar cane. For the first book, you'll need just one piece of leather and three of paper (from three pieces of sugar cane). You can probably get those while setting up a cow farm and a sugar cane farm. If you don't already have a wheat farm, make one to breed the cows.
Once you've made your enchantment table, it will let you make small enchantments, but to get Fortune—let alone Fortune 3 -- you'll need to boost the table's power with bookshelves. You will need a lot of bookshelves, which will require a lot of books, in turn requiring a lot of leather and a lot of paper. (You'll also need wood for the bookshelves, so having a tree farm is handy.) See the Enchanting article for details of how to arrange those.
In order to get Fortune III on an iron or diamond pickaxe you'll need to use nearly 30 levels of experience points per attempt, so a Mob Farm will be handy. While advanced methods are possible, it's fairly easy to build the experience by simply camping at a suitably modified dungeon. It should be noted, that mining ores gives you experience too, and thus you may get a level 30 or so just by mining all the coal you find during chunk mining in one chunk. Enchanting books for Fortune III is a bad idea because, as of 1.5.1, there is only a 0.4% chance of getting Fortune III even at level 30. In contrast, a diamond pickaxe at level 30 has a 7.7% chance of getting Fortune III.
Even after all this building and grinding, it's by no means guaranteed you'll get what you want. If you get Silk Touch instead, you can also use that to collect diamond ore instead of gems. When you absolutely need a few diamonds (say, for a diamond sword), you can always place that many blocks and use another pickaxe to mine them... but save the rest of the ore for when you do get a Fortune pickaxe!
You can also use an anvil to combine weaker items of the same material, turning 2 Fortune I pickaxes into 1 Fortune II, and 2 of those into one Fortune III. Rename the working item early to cut down on retread penalties, and be careful about combining multiple enchantments—the cost can easily make your pickaxe unworkable.
Once you've got a fortune pickaxe, return to mining as usual, reserving this pickaxe for veins of diamond or emerald. (If so inclined, you can use it on redstone, lapis lazuli, or even coal, but using a fortune enchanted pickaxe to mine coal is considered a waste of durability.)
 Repairing Tools
Repairing two tools doesn't just add their durability up - it adds some extra uses as well (5% bonus, 12% for anvils). That can help extend your mining trips with non-enchanted tools. Remember that a crafting-grid repair wipes enchantments, so if you want to keep the enchantments, use an anvil.