Onyx (or Onyx Gem) is the gem that drops when Onyx Ore is mined by a Diamond pickaxe or better. Onyx is used to make a wide variety of items such as Onyx Tools, Onyx Armor, Onyx Bows and Onyx Furnaces and more. Onyx can be obtained by mining Onyx Ore, which will cause the gem to drop from the block, or it can be smelted in a Furnace if Silk Touch is used to mine the ore.