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The cut of a diamond determines its brilliance. While nature determines the color and clarity of a stone, diamond cut is dependent solely upon the skill of the cutter. The cut of a diamond is what determines how the light that enters the diamond is reflected and therefore how much fire and brilliance the diamond will show. A collection of measurements determine the relationship between a diamond's light performance, dimensions and finish. Most gemologists consider cut the most important diamond characteristic because even if a diamond has perfect color and clarity, a diamond with a poor cut will have dulled brilliance.The width and depth can have an effect on how light travels within the diamond, and how it exits in the form of brilliance. |
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Too Shallow: Light is lost out the bottom causing the diamond to lose brilliance.
Too Deep: Light escapes out the sides causing the diamond to appear dark and dull. |
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| Today, gemologists use an optical measuring device, that creates a three-dimensional model to determine the diamond's proportions and angles. The interrelations between these various dimensions will greatly affect how light reacts once it enters and how it behaves once it exits; by using sophisticated computer modeling, it is possible to trace light behavior and measure its levels of brightness, fire and sparkle - the face-up appearance. |
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Diameter: The width of the diamond as measured through the girdle.
Table: The largest facet of a gemstone.
Crown: The top portion of a diamond extending from the girdle to the table.
Girdle: The intersection of the crown and pavilion which defines the perimeter of the diamond.
Pavilion: The bottom portion of a diamond, extending from the girdle to the culet.
Culet: The facet at the tip of a gemstone. The preferred culet is not visible with the unaided eye (graded "none" or "small").
Depth: The height of a gemstone measured from the culet to the table. |
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 Polish and symmetry are two important aspects of the cutting process. The polish grade describes the smoothness of the diamond's facets, and the symmetry grade refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. With poor symmetry, light can be misdirected as it enters and exits the diamond. The polish and symmetry grades are clearly listed in each diamond detail page and within the diamond grading report. For the most beautiful diamond, look for a symmetry grade of excellent (EX), very good (VG), or good (G) for a GIA graded diamond, and ideal (ID), excellent (EX), very good (VG), or good (G) for an AGS graded diamond. diamonds with symmetry grades of fair (F) or poor (P), the alignment of their facets may misdirect light and affects the brilliance of the diamond.
Diamond measurements are calculated and applied to a cut grading scale that makes it easy to understand how well each reflect light: |
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MDC Signature Ideal cut:: Represents roughly the top 3% of diamond quality based on cut. Reflects nearly all light that enters the diamond. An exquisite and rare cut.
Very good cut: Represents roughly the top 15% of diamond quality based on cut. Reflects nearly as much light as the ideal cut, but for a lower price.
Good cut: Represents roughly the top 25% of diamond quality based on cut. Reflects most light that enters. Much less expensive than a very good cut.
Fair cut: Represents roughly the top 35% of diamond quality based on cut. Still a quality diamond, but a fair cut will not be as brilliant as a good cut.
Poor cut: This includes all diamonds that do not meet the performance standards of a fair cut. These diamonds are generally deep and narrow or shallow and wide and tend to lose most of the light out the sides and bottom. MDC does not offer diamonds with cut grade of poor.
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| MDC offers a large selection of certified ideal-cut diamonds. We do not carry diamonds with a poor cut grade , which are either too shallow or too deep to present an acceptable amount of brilliance. |
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For a diamond with the best cut, that will look exceptional even when viewed under a microscope, look to the MDC Signature Collection. These diamonds reflect the most brilliance because they are cut to the most exacting proportions. They have the high polish and symmetry grades available for round diamonds, and our signature princess, radiant, cushion, emerald and asscher cut have either excellent or very good polish and symmetry grades.
For the best value in a brilliant diamond, choose a diamond with a cut grade of good or very good, and polish and symmetry grades of very good or good.
If your diamond has an ideal- or very-good cut with very good or good polish and symmetry, you may want to consider less expensive grades of color and clarity — look for a diamond with H or I color and SI1 or SI2 clarity.
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| GIA bases their new (as of Jan. 2006) cut grade on a combination of face-up appearance, design and craftsmanship elements that all contribute to the diamond's fire and brilliance. They employ a predictive computer model, |
Face-Up Appearance |
Design |
Craftsmanship |
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Brightness |
Weight Ratio |
Polish |
Fire |
Durability |
Symmetry |
Scintillation |
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| based on over 70,000 individual diamond observations and 38.5 million proportion sets, to determine a diamond's brilliance based on its interrelated measurements. Most GIA diamonds graded prior to January 1st, 2006 will not have a laboratory-assigned cut grade. The GIA cut grade system includes ratings of Excellent, Very Good, Good, Fair and Poor. GIA does not assign an Ideal cut and an Excellent rating is their highest grade. For comparison purposes, a GIA Excellent cut will be listed as an MDC Ideal cut on our Web site. The cut grades are equivalent. |
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| The AGSL determines cut grade using light performance, proportion, and finish characteristics to determine a diamond's fire and brilliance. When the AGSL determines a diamond's cut grade, they look at a combination of 11 different criteria in these three categories, and then assign cut grades of Ideal, Excellent, Very Good, Good, Fair, and Poor. |
Light Performance |
Proportion Factors |
Finish |
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Brightness |
Girdle |
Polish |
Dispersion |
Culet Size |
Symmetry |
Leakage |
Spread |
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Contrast |
Durability |
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Tilt |
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| The AGS labels a diamond that meets their standard of perfect proportions, polish, and symmetry as "Cut Grade: Ideal". An AGS Ideal is known throughout the diamond industry as a "triple-zero" grade. An AGS Ideal cut is the equivalent of a GIA cut grade of Excellent or an MDC Ideal cut. For comparison purposes, these cuts are all listed as Ideal on our Web site. |
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| If a GIA or AGSL certified cut grade is not available for a particular diamond, MDC's proportional grading system will determine the diamond's cut. |
MDC Cut Standards
Based on criteria listed on both grading reports:
- Table percentage
- Depth percentage
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MDC uses the measurements from each diamond's grading report to determine:
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- Table percentage: The ratio of the table diameter of the diamond to its overall diameter.
- Depth percentage: The ratio of the depth of the diamond to its diameter.
From these proportions, MDC assigns each diamond a cut grade. |
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