This stuff is fantastic for cleaning light scratches and sometimes worse out of slabs:
As to the question on the whole, I don't think it's so much that the graders don't use durable materials, it's just that people are careless as hell with their slabs. Easily one of my hobby pet peeves, when I buy something that looks good in the pic on eBay, but then a week later the slab arrives looking like someone used it as a cutting board in their kitchen. Invest in some Superior Fit sleeves, people.
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