Tolkowsky Diamonds

In 1919, Marcel Tolkowsky published the first recorded analysis of diamond proportions for the round brilliant cut diamond based on modern theories of light behavior and his opinion of what proportions resulted in what many industry professionals considered to be the best possible balance of brilliance and dispersion of light until the late 1990's.
Tolkowsky's design is referred to as the "American Ideal Cut" and is the basis upon which the modern AGS Ideal Cut Diamond and Hearts & Arrows Ideal Cut Diamond are built on. According to Tolkowsky for optimum brilliance a round brilliant cut diamond should be cut to the following angles and proportions:
34 ½° Crown Angle.
40 ¾° Pavilion Angles.
59.3% Total Depth (excluding girdle thickness) with 16.2% of the depth being comprised of the crown (top half of the diamond) and 43.1% representing the pavilion lower half of the diamond.
53% Table based on diamond's overall diameter.