Specifically, what type of drill bit is required that won‘t chip the tile.
Also do not rush. Slow, slow, slow drill speed and minimal pressure. Having someone spray water while you drill also helps. Getting through the gloss layer is the hardest part as drill will want to slide. The tile bits you purchase at store will wear out after a few holes so keep fresh ones handy.
You need a masonry drill bit, put some electricians PVC tape on the tile and mark that where you want to drill. This stops the drill sliding on the shiny tile surface. Do NOT use the hammer action you would normally use for masonry, just use the drill steadily, once you're through the tile, job done.
I have also used a carbide tipped bit on several occasions to drill tile. The key is to have a sharp bit and to use a pointed center punch to put a very small chip in the surface prior to starting to drill the hole. Make the chip at the center of the point where you want the hole by lightly tapping with a hammer. You don't need much of a chip but it keeps the drill bit from wandering around when you first start drilling. Also a variable speed drill that you can start at a very low speed it also helpful.
There isn't a manufacturer on the planet of tile or drill bits that will ever promise total success. Somewhere will be included a disclaimer stating the obvious (Operator at risk) I use tap con bits for small holes; but even then I like to have a box of extra tiles handy. Part of the issue however; is also the SIZE of the hole/opening; you intend. BTW and with all due respect to any who offer thsi as part of an answer...TAPE will not guarantee that the tile will not chip. Steven Wolf Thousands of sq. ft. of tile
Tile of this type is baked, and is therefore very hard and the glaze is a very slick surface that the drill bit has trouble getting a bite on. You could try using a center punch to mark the hole location, being careful NOT to break the tile; or use a bit made for glass (uses diamond dust and actually grinds the hole rather than drilling it.)
