The distinctive long and large facets of the emerald cut diamond make it easy to love. You’ll often read that an emerald cut has “less brilliance” but this isn't really accurate. The larger facets of an emerald cut return brighter and larger reflections of light back to your eyes: it’s a different optical effect than the smaller but more numerous reflections in a brilliant cut.
Although the quality factors used to evaluate emerald cut diamonds are the same as the 4Cs of round brilliant diamonds, you will probably want to make different choices when you are shopping for emerald cuts.
The factor that you’ll immediately notice first is the length to width ratio: a comparison of how square or long the rectangle of the shape is. A ratio of 1 would be square and a ratio of 1.7 would be long and skinny. Which you like best is a matter of personal taste but most people prefer something in the middle.