Trepanning can also be attainable using a hollow mill. Special form blades may be used with a hollow mill for trepanning diameters, types, and ring grooves. Heat can both strengthen or spoil gemstone shade or clarity. The heating process has long been renowned to gem miners and cutters for centuries, https://clay-shape-cutters33197.diowebhost.com/67673724/5-simple-techniques-for-clay-cutting-tools