The Make : Measurements The measurements of a diamond are primarily used for identification purposes, since no two diamonds are exactly alike in weight, quality and measurements together. However, there is one more important way to use the measurements of a diamond -- to help you assess the beauty. The measurements for round diamonds help you determine symmetry. More perfection means more brilliance in a diamond. For fancy shapes like the marquise or pear shapes, the overall length-to-width ratio is important because certain proportions are more appealing to the eye. For Fancy Shapes For rounds, go directly here. To figure the length-to-width ratio of your fancy-shaped diamond: Take the length of the diamond and divide by the width. Example: If you have a pear shape diamond with a length of 7.5 mm and a width of 5.0 mm -- divide 7.5 over 5.0, and you get 1.50. This means you have a 1.50 : 1 (pronounced: "1.50 to 1") length-to-width ratio. Given below are the length-to-width ratios for each shape that seem to appeal to the most people. This information should only be used as a starting point in the hunt for your personal dream diamond. It would be a great mistake to stick to these ratios precisely, especially against your own personal preferences. It is our advice to start with these ratios for a reference, then look at other options to determine what you like best. Do not let anyone (or the information below) convince you to think differently. Always buy what you like best. The following ratios seem to appeal to the most people: Pear shapes are most popular at: Somewhere between a 1.50:1 and a 1.75:1 ratio Example: 8 x 5 mm is a 1.6:1 ratio Marquise shapes are most popular at: Somewhere between 1.80:1 and a 2.20:1 ratio Example: 8 x 4 mm is a 2.00:1 ratio Emerald cuts are most popular at: Somewhere between 1.30:1 and a 1.50:1 ratio Example: 8 x 5.7 mm is a 1.40:1 ratio Princess cuts are most popular at: Somewhere between 1.15:1 and a 1.00:1 ratio Example: 8 x 7 mm is a 1.15:1 ratio Radiant cuts are most popular at: Somewhere between 1.50:1 and a 1.75:1 ratio Example: 8 x 4 mm is a 1.50:1 ratio Heart shapes are most popular at: Somewhere between 1.25:1 and a 1.50:1 ratio Example: 8 x 4 mm is a 1.50:1 ratio Oval shapes are most popular at: Somewhere between 1.30:1 and a 1.50:1 ratio Example: 8 x 5.5 mm is a 1.50:1 ratio Hint: Do not stick to these numbers too strictly or you will set yourself up for frustration and disappointment at a time when you should be focused on the thrill of love and happiness. Be easy, and create a range for yourself instead of any exact numbers. For Round Brilliant Shapes Obviously, round brilliant cut diamonds will not have more than one diameter... or will they? Actually, all rounds are also given two measurements for diameter, since they are never quite perfectly round. Perfection is impossible since diamonds are created in nature and usually cut by imperfect human beings. The first two figures in the measurements of a round are the maximum and minimum diameters. These two diameters will always vary a little, but should not by very much. Example: A round diamond with measurements of 6.50 x 6.56 x 4.72. This means that the diameter varies by only 0.06 mm, which is quite acceptable for a 1-carat diamond as you will see in the following list. Below are our opinions of acceptable variances for rounds in the popular sizes. Numbers beyond these will affect prices, but only marginally, until the differences are about double these figures: Carat Weight / Acceptable Variation 0.50 carat / 0.05 mm 0.60 carat / 0.06 mm 0.70 carat / 0.07 mm 0.80 carat / 0.08 mm 0.90 carat / 0.09 mm 1.00 carat / 0.10 mm 2.00 carat / 0.12 mm 3.00 carat / 0.14 mm 4.00 carat / 0.16 mm 5.00 carat / 0.17 mm Please Note: Discounts for stones outside of these limits are too difficult to explain here. If you want to learn how to calculate a price for any diamond you want, please see my easy, fast, step-by-step Diamond Pricing Tutorial page. Back to: How to Read a Certificate