Generally, you look at the 4 C’s before buying a diamond, but the shape itself is really important as well. First off, the shape is not cut. The latter is how well the stone can reflect light, while the shape is how it looks physically. The common shapes also happen to be the popular ones, with the round being the most preferred, even among celebrities. The cushion cut has a square shape, while the emerald, radiant, and Asscher cuts make the stone more rectangular. The marquise cut, meanwhile, holds a pear shape. All experts agree that the round brilliant cut is the most popular when it comes to shape, but you could gather as much from simply watching how diamond buyers clamor for 2 carat round diamond engagement rings. Even the selling side prefers it, as do cutters, owing to the fact that the shaping the round cut entails minimal crystal loss. As for the brilliant reflection of light emitted, the round cut reigns supreme, followed closely by the princess cut diamond.