... all kinds of hard stone and concrete, also suitable for geological drills. YWD 2180 complete crystal shape, perfect ... octahedron, good diaphaneity, high impact strength and thermal stability, suitable for high grade cutting, drilling, and grinding tools. YWD 2160 ... full surface, good diaphaneity and low impurity, high strength, suitable for circular saws, frame-saw and geological broaches. YWD 2140 ...