It’s a common standard that using strip or branch mining is the best way to mine for Diamond Ore. Using the standard method of creating a tunnel that is 2 blocks high and 1 wide will be the method that most people are familiar with. This will involve creating a tunnel, skipping 2 blocks and then creating another tunnel. there are many ways to do it and this tutorial will explain the best way to strip mine in Minecraft.
Normally for strip mining you will move down to level 11 and start creating the tunnels with the hope of finding as much diamond as possible. The diagram below will explain the standard method of strip mining in Minecraft. You will mine down where the red lines are pointing, leaving a space of 2 blocks between each mine tunnel that you create.
This method works very well, but it turns out that there are a few methods that you can implement that make strip mining even more efficient. One such method is outlined in great detail in the video below. What it does is take the standard method, outlined above and will add some additional branches to it. The goal of this is to minimize the amount of blocks you need to break in order to find diamonds.
The following video will break down all of the common strategies and shows you the most efficient method to strip mine in Minecraft to yield the most diamonds.