Where are the best places to find diamonds in Minecraft?

Answer 1

hit hardcore then go 12 blocks up, and mine side to side, then i found a bunch of diamond, iron, and coal

Diamonds are found only below level 16 in the ground. (That means lower than 16 blocks before bedrock). However, they are found a bit more common above level 6 and below level 13. But be careful because there are lava lakes around level 10. Tip: When you find diamond ore, a good thing to do is to mine all the blocks around it to make sure there isn't lava to burn it up when you mine it.