Why Diamonds Chip (16.22)
Since diamond is only rated good on the toughness scale chips can occur. Stress in the stone, an inclusion close to the surface, thermal shock (heating and cooling suddenly), or just a sharp blow in the direction of a cleavage plane or single grain. Locations most commonly are an extremely thin or very thin girdle is probably the leading cause, regardless of the crown and pavilion angles. Corners on princess cuts are very common due to the mishandling with steel tweezers or poor setting technique. Marquise ends or a pear shape end is also common.
When a portion of the diamond is chipped away, it is similar to the cleaver
striking a blow and splitting the diamond. When selling a diamond to a private party, it is important to explain that a diamond does chip, and that it is advisable to obtain the appropriate insurance. In addition, some diamond cutters will not guarantee
their work, especially when it comes to inclusions that could potentially cause further damage in the re-cutting process. Do keep in mind since diamond is the hardest natural substance known to man it does have a tendency to be slightly brittle as discussed in subsection 3.05.