Hi,

I am not sure if you are trying to cut straight lines or curves but if its the former you can buy a cutter from good diy stores.

I bought one that is basically thin and longer then the tiles with a big yellow handle that is attached to the diamond wheel. It has a ruler attached to ensure you cut off the right amount. All you do is run the wheel down the tile once and then push the handle down, this breaks the tile on a small bar underneath but in perfect line with the score you made with the wheel.

Mine can cut stone floor tiles as well as terracotta tiles so mirror tiles wouldn't be a problem. I got mine from B&Q in the tiling section - not cheap but I only broke 2 tiles out of 60 in our conservatory so a pretty good success rate.

Sorry can't recall the make - can look if you need it - just ask.