Please read my previous post, Diamonds 101, if you haven't already done so. Let's talk about diamond shapes. The round brilliant is the most popular shape for good reason: it faces up large, and no other shape can perform as well in terms of brilliance, fire, and scintillation. Rounds are also easiest to predict in terms of performance when you only have its specs, so it is a safe bet if you're thinking about purchasing your diamond online. Other shapes are categorized as "fancy cuts": (image taken from Excel Diamonds) The second most popular shape these days is the princess cut. Due to the popularity of princess cuts, their performance is also becoming easier to predict based on just specs and numbers. The princess is probably the most brilliant fancy shape; however,...