Key Points

  • Cut is a diamond's most important characteristic.

  • It has the greatest overall influence on a diamond's beauty.

  • It determines what we generally think of as sparkle.

Blue Nile gemmologists recommend selecting the highest cut grade within your budget. The reason is simple: of the Four Cs, no other characteristic has a greater influence on a diamond's appearance.

A diamond's cut grade is an objective measure of a diamond's light performance, or, what we generally think of as sparkle. When a diamond is cut with the proper proportions, light is returned out of the top of the diamond (which gemmologists refer to as the table). If it is cut too shallow, light leaks out of the bottom; too deep and it escapes out of the side.

Light Reflection of Diamonds

Cut Grades

Blue Nile Signature Ideal cut: Our most brilliant cut, representing roughly the top 1% of diamond quality based on cut. The highest grades of polish and symmetry allow it to reflect even more light than the standard ideal cut.
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: Diamonds that are generally so deep and narrow or shallow and wide that they lose most of the light out the sides and bottom. Blue Nile does not carry diamonds with cut grades of poor.

What Cut Grade Is Right For Me?

For the best possible cut, look to the Blue Nile Signature Collection. Custom made exclusively for Blue Nile, each Signature Collection diamond is hand-selected and cut to the most exacting standards, guaranteeing one of the finest cuts available in the world.
Diamonds with a cut grade of good or very good represent an excellent combination of beauty and value.
Now that you have a solid understanding of how cut affects a diamond's light performance (or sparkle), learn about the second of the Four Cs, colour.

To learn even more about cut, including technical information on light performance, brilliance, fire, polish and symmetry, please visit the tips & hints section. To see the individual parts of a diamond, visit our Diamond Anatomy chart.

Have a question?

Contact us by phone at 00353 1 899 1351 from Estonia, 0800 206 1160 from the United Kingdom, or 00353 1 899 1351 for all other EU countries or email at serviceuk@bluenile.co.uk. In addition, Live Chat is available during most business hours.

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More About Cut

How Does Blue Nile Grade Diamond Cut?
Both the GIA and AGSL evaluate numerous criteria to provide a thorough and accurate diamond cut grade for round diamonds. For other shapes, Blue Nile provides a cut grade that allows you to compare diamonds using consistent criteria. Learn how we determine cut grade.