Minecraft wiki entry for Time-saving_tips, associated text: If for a certain attempt the enchanting table isn't offering Fortune III or Looting III (some very powerful enchantments to have around) on a diamond tool, try an iron one and you might have better luck (due to higher enchantability), and you will at least have something that can help you duplicate important blocks/items just as well as diamond. The effort needed to gain level 1–5 or so is trivial, and so you might consider even putting low-level enchantments even on your expendable tools.