With the growing use of natural stone both in industrial field and in ornamental materials of building, Complex-shaped stone products are being dramatic increasing. It is necessary to machine it with flexible and automatic machines such as NC machining enters. Versatile tools such as shaped diamond mills are used. The wear mechanism of diamond mills in stone cutting is presented in this paper though experiments. The macro-geometries of diamond mills such as mill diameter, profile and weight are described. The changes of macro-geometries of shaped diamond mills can be used to express tool wears. The changes can therefore be used to forecast tool wears in stone machining.