20 Diamonds Right Under Spawn!
Minecraft Seed: Unnatural spawn
If you ever want to play in an average world but do not have the patience to mine your own diamond, then you can play at this seed: Unnatural spawn / (1476757163).
Diamonds can be found here:
There is a nearby village with 2 big houses, a few small houses and many farms. It does not have a blacksmith unfortunately, but you can probably convert one of the mansions into your base.
Potato+carrot at 196, 181.
I believe there are 19-20 diamonds to be found.
It’s clear of lava and water or caves on the way down. You will come across coal and iron if you dig straight down. You can get the diamond tools/armor almost instantly.
(I was playing vanilla survival but after such an absurd find I turned XRAY on. so as a spoiler, there is no more nearby diamond except for 2 and it is a bit far. You might as well ignore it and mine another place much further away).