These diamond sharpening stones came in very nice packaging and arrived on time. After putting in a 1000 grit and running it over the knife, I heard a very harsh scraping noise. Looking at the blade of the knife it looks like I used a rough 100 grit stone. Running my finger over each whetstone I can feel a sharp, raised ridge on 4 edges except 600. This burr looks like it was caused by some means of cutting the base metal into sections and the edges must be removed down to the diamonds. applied to its surface. I don't think using them as a burglary on an unwanted knife blade will just make the problem go away, hence the reason for the low rating. The product's stones are also not perfectly flat, all 4 have an accurate arc and may or may not affect the accuracy of the sharpening. Only 1 of the 4 stones could be used.