Our diamond core drill bits remain one of the most popular tools for drilling through hard materials. Also known as diamond hole saws, these bits are ideal for lapidary, glass, stone, masonry, and concrete, as well as gemstones, ceramics, porcelain, tiles, shell, antler, bone, fossils, and very hard wood. For jewelry-making and precision holes, small diamond drill bits with a solid flat tip are recommended, available in sizes as small as 0.75mm, while slightly larger diamond core drills starting from 1mm are ideal for dense or fused glass. These bits are not suitable for metals or soft wood, which can clog the diamonds; use HSS drill bits for soft metals/wood and carbide bits for hard metals instead. Diamond, being the hardest material, can cut through almost anything, but drilling extremely hard materials like sapphire requires patience and possibly multiple drill bits to achieve the desired result.