The length to width ratio of a marquise 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. Length to width ratios are determined by dividing the length measurement by the width measurement. Measurements are always calculated to the one-hundredth of a millimeter. (Example) Marquise length equals 6.5 millimeters; marquise width equals 3 millimeters; 6.5 millimeters divided by 3 millimeters equals a length-to-width ratio of 2.16 to 1.

The best marquise diamonds will have a length to width ratios between 1.7 to 1 and 2.2 to 1. Length to width ratios within these ranges are considered by GIA as very fine to ideal. Ideal length to width ratio is 2 to 1. Diamonds are rarely cut to perfect 2 to 1 ratio and are rarely found. A marquise 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 2 to 1. If the diamond is within the range of 1.7 to1 and 2.2 to 1, no valuable weight is usually removed.

Marquise diamonds always look slightly 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 marquise diamond that is as affordable as it is beautiful