Round diamonds are the most popular choice for Engagement Rings. Round Diamonds most efficiently manipulate light and therefore have the ability to provide the most shine and brilliance. A diamond’s brilliance is determined by the way light behaves when it enters the top of the diamond. An excellent cut diamond will reflect all of the light that enters a diamond and provide the most shine and brilliance possible.
If a diamond is too shallow, a portion of the light will leave through the bottom of the stone and if the diamond is too deep, the light will be refracted out the side of the stone. This is why it is important to chose a diamond with a proper depth percentage to ensure brilliance.
Round diamonds are classified as excellent, ideal, very good, fair, and poor.
An excellent cut is the highest grade a diamond can receive from the Gemology Institute of American or GIA. Excellent Cut Diamonds have optimal proportions and give the most brilliance and light return.
An ideal cut diamond meets the most stringent requirements from the GIA. The diamond reflects all the light and returns the most brilliance possible.
A very good cut diamond has depth and table percentages that fall just outside the “ideal” requirements set by the GIA. This diamond returns almost all the light and is similar to an ideal cut diamond. A very good cut diamond will sell for less than an ideal cut diamond yet possess very similar characteristics
A good cut diamond reflects most of the light that enters it. A good cut diamond gives you good brilliance and will sell at a much lower price than an ideal or very good cut diamond. “Good” cuts are popular choices for engagement rings.
A fair cut diamond reflects a decent amount of light and will sell for much less than an ideal or very good cut diamond. A fair cut is a popular choice for people who want a decent cost savings to purchase a larger stone.
Suggested Guide for evaluating Diamond Cut
EXCELLENT CUTS FOR ROUND BRILLIANT CUT DIAMONDS [ranges taken from a sampling of over 10,000 diamonds]
Depth… 59.1% to 62.7% [Ideal 60% to 62.9%]
Table… 53% to 61% [Ideal 53% to 57%]
Girdle Thickness… thin, medium or slightly thick
Symmetry… excellent or very good
Polish… excellent or very good
Culet Size… none, very small or small
VERY GOOD CUTS FOR ROUND BRILLIANT CUT DIAMONDS
Depth… 58% to 64%
Table… 52% to 63%
Girdle Thickness… very thin, thin, medium, slightly thick or thick
Symmetry… excellent, very good or good
Polish… excellent, very good or good
Culet Size… none, very small, small or medium
GOOD CUTS FOR ROUND BRILLIANT CUT DIAMONDS
Depth… 57.7% to 64.2%
Table… 55% to 66%
Girdle Thickness… extremely thin, very thin, thin, medium, slightly thick, thick or very thick
Symmetry… excellent, very good, good or fair
Polish… excellent, very good, good or fair
Culet Size… none, very small, small, medium, slightly large or large
FAIR CUTS FOR ROUND BRILLIANT CUT DIAMONDS
Depth… 55.5% to 71%
Table… 54% to 67%
Girdle Thickness… extremely thin, very thin, thin, medium, slightly thick, thick, very thick or extremely thick
Symmetry… excellent, very good, good, fair or poor
Polish… excellent, very good, good, fair or poor
Culet Size… none, very small, small, medium, slightly large, large or very large
POOR CUTS FOR ROUND BRILLIANT CUT DIAMONDS
Depth… 50.8% to 79% [can exceed these limits]
Table… 53% to 70% [can exceed these limits]
Girdle Thickness… extremely thin,very thin,thin, medium, slightly thick, thick, very thick or extremely thick
Symmetry… excellent, very good, good, fair or poor
Polish… excellent, very good, good, fair or poor
Culet Size… none, very small, small, medium, slightly large, large, very large or extremely large
Eric is a diamond engagement ring expert with Since1910.com. As a fifth generation jewelry store with over 99 years of experience, we provide expert diamond guidance. We are members of the Prestigious American Gem Society, Jewelers Vigilance Committee, Better Business Bureau and Retail jewelers of America.
