... 4.0mm Weight: 1ct for 5pcs, 1ct for 7pcs, 1ct for 8pcs, 1ct for 9pcs, 1ct for 12 pcs, 1ct for 17pcs etc. Grade: YWD 25, YWD ... 30, YWD 50, YWD 70 for ... , good diaphaneity, high impact strength and thermal stability, suitable for high grade cutting, drilling, and grinding tools. YWD 2160 complete crystal ...