Jadnashua
Retired Defense Industry Engineer xxx
A cutoff wheel on an angle grinder would work. But, depending on the type of tile (some is quite soft, some is nearly as hard as diamonds), you might be able to drill a series of holes, then crack it out. A softer tile might also work with a carbide saber saw blade, but it won't work on a good porcelain. THere are some diamond blades and bits for things like a RotoZip, if you have one of those tools. While expensive, a nice round hole could be made with a diamond core bit. Take all of a few minutes, and perfectly smooth. You might be able to rent one, but those generally should be used wet. You might find one for dry cutting, though.