Diamond Cut

Buying Tips

  • Cut is the most important of the 4Cs because it has the greatest influence on a diamond's sparkle.
  • Even if a diamond has a perfect clarity and colour grade, if it has a poor cut, it may appear dull.
  • 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.
  • To maximise your budget, choose the highest diamond cut grade your budget allows. We suggest a cut grade of Very Good or better.
Light Reflection of Diamonds

Grading Scale

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

Diamond Cut Grade Chart

Less Than 1%

Astor by Blue Nile™

Every Astor by Blue Nile™ Diamond is cut to gather and reflect the most light possible. Light performance is measured by three factors: brilliance, fire and sparkle. Fewer than 15 out of every 10,000 diamonds qualify as an Astor by Blue Nileā„¢ diamond.

See Astor by Blue Nile™ 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.

More Expert Tips

  • For the best possible cut, consider Astor by Blue Nile™. Only diamonds with the highest brilliance, fire, and sparkle are considered as an Astor by Blue Nile™ diamond. Each diamond is graded by both the Gemmological Institute of America and GemEx to guarantee its quality and sparkle.
  • 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.

Next, learn about Diamond Colour.

Have A Question?

Contact us by phone at 00800-2583-6453 from Switzerland, 0800 098 8541 from the United Kingdom, or 00353 1 899 1351 for all other EU countries or email at service@bluenile.co.uk.
In addition, Live Chat is available during most business hours.