The 4 C's and Comparison Shopping
The Shape of Things
Shape is mostly a matter of taste, but you should understand that you give up some sparkle to have shapes other than round. If all other factors are the same (color, clarity and carat weight), fancy-shaped diamonds sparkle less than a comparable round brilliant, because the angles required by the fancy cut allow light to escape rather than reflect.
All other factors being equal, shape can also affect cost by up to 40%. In order of expense, from highest to lowest, the shapes are:
With rectangular or square shapes, there is a further price distinction. Faceted "squares," like the Princess or Radiant, cost 3% to 5% more than step-cut stones.