Diamond Cut

Key Points

  • Of the 4Cs, cut is the most important characteristic because it has the greatest influence on a diamond's sparkle. Simply put, the better the cut grade, the more it will sparkle.
  • Even if a diamond has a perfect clarity and colour grade, if it has a poor cut, it may appear dull.
  • Gemmologists recommend choosing the highest cut grade within your budget. Very Good or better, if possible.
Light Reflection of Diamonds

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.

Grading Scale

Use the slider to see cut grade details or view the Cut Grade Chart below.
Poor/Fair
Good
Very Good
Ideal
Signature
Poor/Fair Cut
Represents roughly the top 35% of diamond cut quality. These diamonds tend to appear dull or glassy.

Diamond Cut Grade Chart

Top 1%

Blue Nile Signature Cut

Our most brilliant cut represents roughly the top 1% of diamond cut quality. The highest grades of polish and symmetry allow it to reflect even more light than the standard ideal cut.

See Signature Cut Diamonds
Top 3%

Ideal Cut

This rare cut represents roughly the top 3% of diamond cut quality. It reflects most light that enters the diamond.

See Ideal Cut Diamonds
Top 15%

Very Good Cut

This cut represents roughly the top 15% of diamond cut quality. It reflects nearly as much light as the ideal cut, but for a lower price.

See Very Good Cut Diamonds
Top 25%

Good Cut

This cut represents roughly the top 25% of diamond cut quality. It reflects most light that enters, but not as much as a Very Good cut grade.

See Good Cut Diamonds
Top 35%

Poor/Fair Cut

Represents roughly the top 35% of diamond cut quality. These diamonds tend to appear dull or glassy.

Low grade not offered by Blue Nile.

Expert Buying Tips

  • 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.

To learn more about cut see Diamond Anatomy and GIA-AGSL Cut Grading Criteria.

Next, learn about Diamond Colour.

Have A Question?

Contact us by phone at 00353 1 899 1351 from Lithuania, 0800 098 8541 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.