Brilliant cut
A brilliant is a diamond that has been cut in a classic round shape with 57 or 58 facets to achieve maximum light reflection. Many people mistakenly believe that a brilliant and a diamond are two different things, but "brilliant" simply refers to a specific cut. This cut is the most popular, as it allows the diamond to achieve maximum light reflection.

The modern brilliant cut was developed in 1919 by Belgian mathematician Marcel Tolkowsky. He calculated the optimal balance between light reflection and color dispersion and created a design with 57-58 facets that maximizes the brilliance and fire of the diamond. Tolkowsky's principles still form the basis of the brilliant cut today.

Hearts and Arrows
A Hearts and Arrows (H&A) diamond is a specially cut round brilliant cut diamond in which the facets are perfectly symmetrical. This creates a distinctive pattern that can be seen through a specialized H&A scope:

Viewed from the top: Eight perfect arrows.
Viewed from the bottom: Eight heart-shaped figures.