Instruct: Classify Amazon reviews into positive or negative sentiment
Query: poor wear qualities

I bought two of these stones, a fine and super fine. They remove a lot of metal from the blade, so you have to be careful to only use them for an initial honing. The biggest dislike is how rapidly the stones wear. They are supposed to be diamond but seem to wear very fast. Although they remove metal rapidly at first they wear down quickly and become super super fine after a couple on knife are sharpened.