How to find diamonds on minecraft xbox 360?

If you dig down to I think it's x-12 and strip mine it's a bit easy. Sometimes you can find them around lava in deep caverns if you're careful.

Use a map find y coordinates 12 then go and strip mine diamonds spawn near diamonds a lot but you can strip mine and find them too

It's really quite simple. Dig a stairway design going underground until you reach about about level 8, and then stop going down. Begin digging horizontally away from the stairs, making sure the ceiling reaches up to about level 12 - 13. From this single shaft, begin mining away at right-angles, ensuring the ceiling height is always the same, and the width of each shaft is 1 block wide. Once you've gone as far as you think is necessary, backtrack to the main shaft, move along 2 blocks and start a new shaft at right-angles to the main shaft. Keep doing this, always keeping each new shaft 2 blocks apart from each other.

By maintaining this form of mining, you ensure that with every new shaft you expose new blocks above, in front, below and on either side of you, without inadvertently hiding potential diamond locations.

REMEMBER! Sometimes diamonds will spawn in an odd manner, so if you only find 1 or 2 in a single area, mine the blocks around it and diagonally from it to ensure you've got them all.