EMERALD CUT
The Emerald cut diamond is different as the pavilion facets are rectangular. Due to to the wider rectangular facets and an open table this shape is a far more honest stone highlighting the clarity of the diamond. I would recommend going for a high clarity in this type of diamond due to this reason. The length-to-width ratio will effect the look of the stone from above. This Ratio is shown in the diagram.
For a traditional Emerald cut diamond the Length-to-width ratio should be between 1.30- 1.40