What is the best weapon for digging deep down to gold and diamonds in minecraft?

Iron Pickaxe

Diamond Pickaxe for digging stone, diamond shovel for digging sand, firt and gravel, and then use the diamond pickaxe for mining the diamond and gold If you don't already have diamond to maek these tools use iron.

Iron pickaxe and iron shovel for dirt and gravel. Getting gold is pretty pointless, mines faster than iron but had terrible durability.