Review on Diamond-Coated Ceramic Marble at Flyshop by Michael Boyd

Tickled for money with performance. Don't turn too fast and use a water deflector to keep the bit cool. Worked way above expectations for what I paid for 10 of them. A drill bit was enough for a full cut of just over 1 inch. Note that I had to poke the cut out to get over an inch deep as these bits only stopped an inch due to a small taper at the tip.