The sharpening of a diamond tool is a very delicate process and must be carried out by qualified centres; to ensure maximum tool safety, it is necessary that the tip seat remains intact as otherwise the tip might break away from the tool during use.
Every sharpening procedure erodes about 0.2 – 0.3mm from a single diamond tip. That’s why, for example, cheap tools with a thin tip can’t be sharpened more than 2 or 3 times, while thicker tips can be sharpened about 8/10 times.