To make a brooch, mine either copper rocks or tin rocks with the dwarven army axe until you get an uncut lapis lazuli, which can then be crafted into a lapis lazuli gem with the dwarven army axe or a chisel. Then chop regular trees, dead trees or evergreens, also with the axe, until you get a wooden knot. Craft this into an unfinished wooden brooch with the dwarven army axe or a chisel, and then attach the lapis lazuli gem to it to get a lapis lazuli brooch.