Diamonds can be cut into many different shapes. The person responsible for making a diamond is called a cutter. The cutter is responsible for making the diamond look the way it does. This proficient individual uses dust from a diamond on a special polishing wheel to cut a new diamond. These cuts are flat surfaces called diamond facets. Because the cutter has to think about symmetry, length, depth and height of each facet, it is seen as a highly regarded skill in the jewellery industry to cut diamonds.
Facets are the surfaces of a diamond that can be polished. These facets can then refract the light within the diamond and give off the spectrum of beautiful colours. In the jewellery world this is known as the fire, sparkle or luster of the diamond.
Because every facet has the potential to change a light ray’s plane of travel, every facet must be considered in any complete calculation of light paths. Just as a two-dimensional slice of a diamond provides incomplete information about the three-dimensional nature of light behavior inside a diamond, this two-dimensional slice also provides incomplete information about light behavior outside the diamond. A diamond’s panorama is three-dimensional. Although diamonds are highly symmetrical, light can enter a diamond from many directions and many angles. ref: wikipedia
Anatomy of diamond facets
We also have a wide selection of diamond Education articles that you might find helpful.