It is essential to use the correct cutting blades for the type of paving you have.

For concrete and natural stone paving you should use a diamond blade disc cutter and with porcelain paving, a specific porcelain blade should be used.

With porcelain especially, a wet cut is necessary to avoid the paving overheating and cracking. Cut slowly and try to avoid the stone vibrating - sometimes it helps to cut porcelain paving on sand to avoid excessive vibration. 

Always wear a mask and suitable safety equipment such as ear defenders, gloves and safety footwear when cutting paving.