ROUND BRILLIANT CUT DIAMONDS

 

Cut Grade Standards   1A - Table % = 53-54% "Ideal Cut" 1B - Table % = 55-57% 2A - Table % = 58-59%     "Premium Cut" 2B - Table % = 60-61% 3A - Table % = 62-63%     "Choice Cut" 3B - Table % = 64-65% 4A - Table % = 66-67%     "Value Cut" 4B - Table % = 68% +

 
Since a Round Diamond is completely symmetrical and capable of reflecting nearly all the light that enters, it is the most brilliant of all diamond shapes. Fancy Shape Diamonds - or any diamond shape that is not round - follow different proportion guidelines.
 
Without the benefit of a round refractive pavilion, light can filter directly through an area in a Fancy Shape Diamond, creating a window that you can see right through. In some diamond shapes, this area takes on the shape of two offset triangles, creating an effect called a "Bow-Tie". The more prominent the "Bow-Tie", the less brilliant the diamond. An "Ideal-Cut" Fancy Shape Diamond has no noticeable "Bow-Tie".