... Weight: 1ct for 5pcs, 1ct for 7pcs, 1ct for 8pcs, 1ct for 9pcs, 1ct for 12 pcs, 1ct for 17pcs etc. ... , YWD 70 for different purity. YWD 50 and 70 is the best quality stones made in lab ... , high impact strength and thermal stability, suitable for high grade cutting, drilling, and grinding tools. ... diaphaneity and low impurity, high strength, suitable for circular saws, frame-saw and geological broaches. ...