the right is the output.
this is handy because of the silk touch enchantment.
also i read it wrong, i thought you are able to smelt a diamond to a diamond just for the lulz. diamondOre to diamond isnt a big deal. sry.
well, the secret at least is not a recipe, or it's coded elsewhere, where you wouldn't expect it. don't want to search for that one though
I think he's just trolling, to get interest.