What is a carborundum stone use for?

I just viewed a Fine Gardening video on sharpening gardening clippers. He used oil on the carborundum stone, then finished up with a "diamond stone" which he had sprayed water on. I think both...

First, select the stone you want to use in your items bag. Then, select 'use' on the item's menu. Finally, select the Pokemon that has the word 'Able' next to it to evolve it using a stone.

Early people chose stones as there tool because stones made hunting,making clothes,grinding,and shaping things easier

because they are rare you just cant find them anywhere

use a leaf stone