RU2414550C1 RU2009128751/05A RU2009128751A RU2414550C1 RU 2414550 C1 RU2414550 C1 RU 2414550C1 RU 2009128751/05 A RU2009128751/05 A RU 2009128751/05A RU 2009128751 A RU2009128751 A RU 2009128751A RU 2414550 C1 RU2414550 C1 RU 2414550C1 Authority RU Russia Prior art keywords approximately abrasive grinding plane sapphire Prior art date …