It’s all about science and physics. By far the most preferred diamond shape, the round (aka the brilliant cut) is also the most optically brilliant because of its 360-degree symmetrical shape. A round brilliant is a great choice if you want the most sparkle and the most enduring classic shape. The round shape has been cut for centuries, but in 1919, Marcel Tolkowsky defined specific angles and proportions to yield the most brilliant diamond, which form the basis for the modern “Ideal” cut round-brilliant diamond. Round-brilliant diamonds are the only shape to have this ideal proportion defined. The round silhouette works with almost every mounting, from classic solitaires to the most avant–garde designs. Rounds can be set into four or six prongs, based on the design of the setting, or into bezel mountings (a metal band that runs around the edge of the diamond to hold it securely in the setting). In general, if the round brilliant has an Ideal cut (which all Ziamonds do), you want the setting to have the least amount of metal around the stone so that it is held securely but does not cover up too much of the diamond and block light from entering the stone. light is the life source of brilliance for all gems. Even today, the most popular shape and size of diamond engagement ring sold world wide is a 1 carat round.