I've got a full stack plus twenty or so in my nomad world, all legit. Used to have over 40 in my second stack, but I made diamond armor for the journey.
I honestly don't find diamonds that rare. I see them quite frequently. Finding slimeballs. Have yet to find one on my own. I've found one slime legit by myself in my Minecraft HISTORY, and I didn't get a slimeball from it. But I'd say... around 30 diamonds. Give or take. I've put them all in blocks though. On one server I had almost 9 blocks of them. Meh...
Non-legit- Lost count lol.
I usually mine at layer 12.
But then I rage-quit after finding I needed 8 more blocks and 5 raw to make what I need. (gem of eternal density.)
"I only devoured two men"