Diamond cut refers to the proportions of a faceted diamond, the shape and positioning of its facets, and the general form of the stone. Cut is different from shape, which is a narrower characteristic referring only to the profile of the stone as viewed from above.
The way a diamond is cut determines how its facets will reflect light back to the eye of the observer – this is also called “light performance”. Light performance is extremely important for maximizing a diamond’s fire and brilliance.
Better-cut diamonds are more brilliant, and as a result, their inclusions are less visible. In fact, cut plays a much more important role in making a diamond look brighter than clarity.