Diamond cutting is the art, skill and, increasingly, science of changing a diamond from a rough stone into a faceted gem. Diamond cutting requires specialized knowledge, tools, equipment, and techniques because of its extreme hardness.

'Cut' has two meanings in relation to diamonds. The first is the shape: round, oval and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are very hard to cut, special diamond bladed edges are used to cut them.

Diamond manufacturers analyse diamond rough from an economic perspective, with two objectives steering decisions made about how a faceted diamond will be cut. The first objective is that of maximum return on investment for the piece of diamond rough. The second is how quickly the finished diamond can be sold. Scanning devices are used to get 3-dimensional computer model of the rough stone. Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone.

The process of maximising the value of finished diamonds, from a rough diamond into a polished gemstone, is both an art and a science. The choice of cut is influenced by many factors. Market factors include the exponential increase in value of diamonds as weight increases, referred to as weight retention, and the popularity of certain shapes amongst consumers. Physical factors include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated.