The Simple Refinement mod is a great way to bridge the gap between iron/gold ores and diamond. This simple mod allows you to smelt iron and gold one more time to become “refined”.
What this means is that these will now retain a 50% increase in durability when used in tools. So while these won’t be as strong as diamond still is, they will help when you haven’t been able to find as much but iron and gold are a plenty.
This is especially helpful if you’re playing on a harder survival mode and it doesn’t give you too much of an edge over vanilla. This mod gives you just enough to help speed things along and it’ll give a slight advantage to all tools capable of being crafted with gold and iron.