A diamond measures a 10 on the Mohs Scale of Hardness, making it the hardest natural substance known to occur on Earth, and many consumers are curious about how diamonds are cut if they are so hard. There are a number of techniques used in diamond cutting including basic cleaving and the use of a grinding wheel called a scaif. These techniques have been developed over centuries of jeweling, and most diamond cutters use techniques that were originally developed hundreds of years ago, because they are still the best way to handle diamonds. Diamond cutters usually combine several processes to create a sparkling, faceted gem from a rough diamond, in a painstaking job where the stone may lose as much as 60% of its weight.

The most ancient diamond cutting process is cleaving. To cleave diamonds, the diamond cutter places a chisel at a point of weakness in the stone and taps it with a mallet, causing the diamond to split. If the weakness was misjudged, this can destroy the diamond. If the diamond cutter judged correctly, the stone will be split into workable pieces which can be individually refined. Medieval diamond cutters cut their cleaved stones with other diamonds, lubricating the surfaces with oil and grinding away at the stone to reveal facets. Some diamond cutters still use other diamonds as part of their cutting and polishing process.

In the fifteenth century, the scaif was developed. A scaif is a polishing wheel for diamonds which is kept liberally lubricated with oil and diamond dust. A diamond cutter can use a scaif to polish a diamond held in a dop, a padded diamond holder which protects the diamond while it is being worked on, only revealing the side of the diamond that is currently being polished. The scaif changed the face of diamond cutting, allowing cutters to create symmetrical and even facets which brought out the true sparkle and shine of a diamond. By playing with angles, diamond cutters created unique and beautiful gems for setting in jewelry.

In the twentieth century, another tool was added to the diamond cutting arsenal: a diamond saw. Diamond saws are steel blades which are lubricated with an oil and diamond dust mixture that is continually reapplied as the diamond is worked. Because diamond saws can generate a great deal of heat, diamonds may be cooled as they are worked on in special cooling holders. This is also the case with a scaif, and is one of the reasons that cutting diamonds is such a painstaking process, because the diamond cutter must take a break every time the stone starts to warm up. If the stone contains any water while it is being cut in small bubbles or hairline cracks, the heat can cause the water to boil, and the diamond may crack or explode.