The Vitrex Dry Cut / Wax Filled Drills have a diamond grit edged bit to provide a faster, superior cut and give them an increased life. The bits are wax filled so there is no need for water. Ideal for drilling in all tile types, including porcelain.
.......And in this case where these drill bits can be expensive, you are better of paying the high prices. This drill bit only completed half of one hole and I have drilled many before with other bits.