People often use the word "cut" to describe the stone's shape. The shape is a diamond's outline. The term "cut" is used to describe a shape and the pattern, proportion, position, and shape of its facets. There are two distinct types of faceting: step-cut and brilliant-cut.
Step cut facets are trapezoids and rectangular. Brilliant cut has kite-shaped and triangular facets. A cut has a significant effect on a diamond's optical properties, how well it reflects and breaks the light. A precursor of the ideal cut, the "American Standard" cut was developed in 1919 by a Polish engineer Marcel Tolkowsky. His formula was perfected over the years, eventually resulting in the ideal diamond cut. The cut grades are "poor," "fair," "good," "very good," and "excellent."
Round brilliants with excellent cut, symmetry, and polish grade are called "ideal cut diamonds." Sometimes these diamonds are called "Triple X", "XXX", "ExExEX". Some ideal cut diamonds with a specific pattern of facets can be classified as "Hearts and Arrows", or "Hearts & Arrows". Our opinion is that a small degree of asymmetry is beneficial for a diamond. A super symmetrical diamond lacks the precious randomness of the reflections that make a diamond come alive.