Does this help?
You really grind the hole. I use my Dremel. First mark your china with Sharpie, then build a well using clay or anything that will hold water around your mark. Put water inside the little well and grind the hole. The water is an important part of the process.
I would use a 6mm Diamond Core Drill (often referred to as Diamond Hole Saw Drills) or if you're using a Dremel drill you might like to use a 6mm Bottle Neck Diamond Core Drill
Need a drill bit for tile