How crafting diagrams work in The Witcher 3
A diagram is the permission slip for a piece of gear in The Witcher 3: without it a blacksmith will not take the job, however many components you are carrying. Each diagram names the item it produces, everything it consumes, and the craftsman rank required.
Rank matters as much as the components. A journeyman cannot forge a master-tier Witcher 3 diagram, so the limit on a build is often which smith you have found rather than what is in the satchel.
Witcher 3 gear ladders and what they consume
Witcher school gear runs on diagrams more than anything else, since every tier is built on the one below it. The Witcher 3 gear sets page lays those ladders out end to end, from basic through to grandmaster.
What each diagram consumes turns up on the crafting components page, which is the faster way round when you have the materials and want to know what they make.