A Diamond Core Bit, comes in various sizes, recommend the Sutton Brand, top shelf almost impossible to get any better, although relatively expensive as 76mm m14 bit at bunnings is priced at about $150, but you did ask for best drill bit

Thanks so much. It will save me that in time.

You can buy a glass and tile drill bit for $15. It looks like it has a triangle on the end of it and is great for drilling holes in all tiles

What are you trying to achieve? Water/tap outlet, rail install ??? Different bit for different job.

We have just cut holes in our ceramic tiles for taps etc using the diamond coated hole saw as suggested by JPM, however we certainly didn't spend that sort of money. My husband ordered some online from China for about $3 and they did the job perfectly. Unless you do it for a profession, I wouldn't spend that much on something you will use like 10 times.