Ideal proportions of a Round Cut Loose Diamond

How to determine the ideal proportions of a Round Cut Loose Diamond?

The ideal proportions of a loose diamond can be difficult to figure out when you’re not a gemologist (someone who has studied diamond and gem stones by accredited associations such as GIA).  Diamond grading laboratories have made it easier for the typical diamond consumer to educate themselves in diamond terminology.  GIA has created a quick tutorial on their website.  Although their website can be a little confusing its good for those looking for a more detailed explanation.

The simplest way to determine if a diamond has ideal proportions and is considered a very brilliant diamond, is to check its Cut Grade.  The Cut grade can be one of the following: Excellent (Ideal), Very Good, Good, Fair, and Poor.  Typically you would want to stay away from any cut grade below a Good grading.  Fair and Poor grades are not so easily assigned to a diamond and determine that the diamond has been very poorly cut by the diamond manufacturer.  Excellent and Very Good are great remarks on a diamond’s Cut grade and would produce the most amount of brilliance (sparkle) on a diamond.  This means the diamond has been cut in the most productive way to allow the most amount of light to be reflected from the diamond.

EGL also has Cut Grade on their certificates.  They’ve also added another tool to help customers determine if a diamond is well cut: Comments.  Comments on the certificate are usually toward the bottom of the diamond detail report.  Comments such as Excellent Ideal Cut, Premium Cut, Hearts & Arrows , to name a few.  If you find any of these comments on the diamond certificate you should be reassured that the diamond is very brilliant.  Hearts & Arrows are comments used when the diamond has a certain proportion that creates an illusion of Hearts & Arrows in the body of the diamond when viewed face up using a microscope.  Most certificates will illustrate a picture of the Hearts & Arrows on the report so customers know what they look like.

Cut grades and comments are only used for Round Loose Diamonds.  Other diamond shapes require more knowledge and are not as easily identifiable for ideal proportions.  If you are interested in learning more about the different diamond shapes and what make them ideal please don’t hesitate to contact us at