To create a Diamond Golem in Minecraft, you'll need to craft a snow golem out of two blocks of snow and a carved pumpkin. Once you have the snow golem, you'll need to find an area where you can build an enclosure for the golem. You'll then need to build the enclosure and fill it with diamond blocks. To complete the golem, you'll need to use any pickaxe to mine, break, and collect at least 16 blocks of diamond from your enclosure.
Once you have the blocks, you'll need to put them in your inventory. Next, you'll need to move to the top of the snow golem's head and right-click it with the diamond blocks. This will cause the golem to transform into a diamond golem. The diamond golem will have four times the strength and health of a regular snow golem, and will also deal additional damage to any hostile mobs it encounters.
Congratulations! You have just made a diamond golem in Minecraft.