A chisel and hammer can be used when cutting a diamond.
A diamond measures 10 on the Mohs scale of hardness, making it the hardest natural substance on Earth. This raises the question of how the stones are cut if they are so hard. There are several techniques used in diamond cutting, including the basic cut and the use of a grinding wheel called a scaif. These techniques were developed over centuries of jewelry making, and most cutters use techniques originally developed hundreds of years ago because they are still the best way to handle gemstones. Diamond cutters often combine several processes to create a brilliant faceted gem from a rough stone, arduous work in which the stone can lose up to 60% of its weight.
Diamonds are often cut with tools that contain diamond dust.
The oldest cutting process is cutting. To cut a diamond, the cutter places a chisel on a weak spot in the stone and hits it with a hammer, causing the gem to crack. If the weakness is misjudged, it can destroy the stone. If the diamond cutter is judged correctly, the stone will break into workable pieces that can be individually refined. Medieval cutters cut their cracked stones with other diamonds, lubricated the surfaces with oil, and polished the stone to reveal the facets. Some cutters even use other gemstones as part of their cutting and polishing process.
Chocolate diamonds in a variety of cuts.
In the 15th century, the scaif was developed. The scaif is a polishing wheel that is kept liberally lubricated with oil and diamond powder. A cutter may use a scale to polish a gem held in a dop, a padded support that protects the stone as it is worked, revealing only the side being polished. The scaif has changed the face of the diamond cut, allowing cutters to create even, symmetrical facets that bring out the true brilliance of the gem. Playing with the angles, the cutters created beautiful and unique jewels to place in the jewelry store.
diamonds
In the 20th century, another tool was added to the diamond-cutting arsenal: a diamond saw. These saws are steel blades lubricated with a mixture of oil and diamond powder that is continually reapplied as the stone is worked. Since saws can generate a lot of heat, stones can be cooled while working on special cooling stands. This is also the case for scaling, and it’s one of the reasons cutting gemstones is such a labor-intensive process, because the cutter must pause each time the stone begins to heat up. If the stone contains water in small bubbles or hairline cracks while it is being cut, the heat can cause the water to boil and the stone may crack or explode.