I actually did find some deepslate coal ore

Regular diamond ore today

Don't forget deepslate emerald ore
There are only a few blocks where it can spawn for each world

true

What about nether gold

Man, I find that all the time

it is everywhere in the nether

Deepslate emerald is still rarest, at least from what I've seen. Nether gold is a little less common than nether quartz, but can be found in most nether biomes. Deepslate emerald needs to be at a very specific y-level, and be directly under a mountain or extreme hills biome.

What?

Actually, emerald was once more rare than diamonds before 1.18