The length to width ratio of a oval shape diamond is important to its value. Popular diamond quality reports from GIA and other gemological laboratories do not provide length to width ratios. However, they do provide  length, width, and depth measurements. Measurements are always calculated to the one-hundredth of a millimeter. The best oval diamonds have a length-to-width ratio that is between 1.3 to 1 and 1.7 to 1. The length-to-width ratio is calculated by dividing the length of the marquise by the width. (Example) Oval length equals 6 millimeters; oval width equals 4 millimeters; 6 millimeters divided by 4 millimeters equals a length-to-width ratio of 1.5 to 1.

Diamonds are rarely cut to a perfect 1.5 to 1 ratio. This is a request that can rarely, if ever, be filled. An oval diamond's length-to-width ratio is largely determined by the original size of the rough diamond crystal. When a rare, fine quality diamond is cut by an experienced diamond cutter, the weight and value will never be sacrificed simply to make a diamond's length-to-width ratio 1.5 to 1. If the diamond is within the range of 1.3 to 1 and 1.7 to 1,extra weight is usually not removed. GIA has established these length-to-width ratios shown are considered in the range of very fine to ideal.

Oval diamonds always look longer after the diamond has been set in the proper setting. Take this time to return to our list of certified diamonds to choose the perfect oval diamond that is both affordable and beautifully shaped.