Review on 6-Piece Dry Diamond Drill Bit Set For Granite, Marble, Ceramic, Stone, And Glass With Hex Shank - Ideal For Porcelain Tiles - Sizes Include 3/16", 1/4", 5/16", 3/8", 1/2", And 9/16 by Keith Wolff

Overall, these are neither pretty nor cheap, but they are effective. I have had terrible luck with traditional bits on difficult surfaces like ceramic and glass and broke more of my wife’s pottery than I have successfully drilled drainage holes through. Since pottery isn’t cheap—especially the sort of pottery my wife is a fan of—I needed something that would work. These diamond bits did, though there is a learning curve so I used a few scrap tiles to get the hang of it. You need to start the hole at an angle before drilling vertically, and patience is a virtue for this application – slow is smooth in this case.This set offers a good variety of bits for an assortment of holes, and I think you can reasonably be expected to get several holes per bit.The four-star rating is reflected based on a combination of value and craftsmanship. Pricewise, these are marketed at the high end of comparable products. Separately, the bits I received had some surface abrasions on the shaft where the paint had chipped off in transit suggesting it’s a superficial coat and unlikely to last. I don’t buy my bits for appearance and expect performance over aesthetic. In that regard, this product met that mark.