Emerald (as well as Asscher cuts) are a class of diamond cuts known as “step cuts.”
According to Wikipedia: Stones whose outlines are either square or rectangular and whose facets are rectilinear and arranged parallel to the girdle are known as step- or trap-cut stones.
Emerald cut rings makes the gem appear larger. Since more of the gem’s surface area is exposed (on average, an emerald cut has a 5% greater surface area than a 1 carat round cut diamond, for instance), the top surface of an emerald cut diamond appear larger.Emerald cuts make fingers appear more slender. Because emerald cut diamonds are more elongated, they give the illusion of longer, more slender fingers.Emerald cuts are more affordable. (Yes, we saved the best for last!) Since they are a more unusual cut than princess-cut or round cut gems, they’re also in less demand and more cost efficient.