Astor Education

What's an Astor by Blue Nile™ diamond? Discover how we create a diamond guaranteed for unmatched sparkle.

Light Performance

Every Astor by Blue Nile™ diamond is specifically cut to gather and reflect the most light possible. Light performance is measured by three factors: brilliance, fire, and sparkle. Every Astor by Blue Nile™ diamond receives the highest grade for each by GemEx, the leader in light measurement.

Light Performance video

Astor by Blue Nile™ compared to a standard diamond


The amount of bright white light that is reflected out of the diamond is also known as brilliance. The flashes of white light contribute to the overall sparkle of the diamond. Astor by Blue Nile™ diamonds must reach a brilliance grading of "Very High" by GemEx, their highest grade.

Example of a Very High Brilliance rating from GemEx


Fire is the measure of colored light a diamond emits. As light enters and then bounces out from the diamond, the diamond's cut angles split the various hues, creating flashes of vibrant colored light. Only diamonds with Fire grades of "Very High" on the GemEx scale - the highest grade - qualify as Astor by Blue Nile™ diamonds.

Example of a Very High Fire rating from GemEx


When you put brilliance and fire together, you get sparkle. As a diamond rocks back and forth, each individual facet comes alive with flashes of both brilliance and fire. This display is known and measured as sparkle. Every Astor by Blue Nile™ diamond is specifically cut to achieve an unmatched sparkle that commands the attention of every eye in the room.

Example of a Very High Sparkle rating from GemEx

What Sets Astor by Blue Nile™ Apart?

Exceptional Rarity

Not just any diamond can make the Astor by Blue Nile™ cut. Astor by Blue Nile™ diamonds are sourced only from premium quality rough with as few impurities or inclusions as possible. Each diamond is hand selected and guaranteed to have no inclusions visible to the naked eye.

Exceptional Rarity

Diamond Rough Diamond Cut Plot

Superior Cut

Cutting a diamond from its rough form is the most crucial step in creating a diamond with extraordinary sparkle. As much as 74% of the rough is sacrificed to achieve the best possible cut. Every Astor by Blue Nile™ diamond ranks as an Excellent Cut from the Gemological Institute of America - the world's most respected independent laboratory - which assesses the angles, symmetry, and proportions of a diamond. The diamond is then graded by GemEx, the leader in light measurement. Only 1 out of every 1,000 diamonds qualifies as an Astor by Blue Nile™ diamond.

Astor Ideal Cut

1.00 Carat
Rough Lost: 55-74%

Very Good Cut

1.10 Carat
Rough Lost: 50-68%

Good Cut

1.20 Carat
Rough Lost: 45-66%

Ideal Proportions

The proportions of a diamond affect the way that light travels through it. If a diamond is cut even slightly out of proportion, whether too shallow, wide, deep, or narrow, it will restrict the amount of light that can reflect out of the diamond. Every Astor by Blue Nile™ diamond is cut to ideal proportions to reflect light and ensure maximum sparkle.

Exceptional Symmetry

The facets of a diamond act as a mirror. Precise symmetry ensures that each facet of the diamond is evenly aligned to reflect the maximum amount of light, otherwise light entering the diamond is misdirected, causing it to sparkle less. Astor by Blue Nile™ diamonds are cut to achieve precise symmetry for maximum sparkle.

Exceptional Symmetry


The extraordinary sparkle of Astor by Blue Nile™ is available in popular round and princess cuts.

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Double Certified

Astor by Blue Nile™ diamonds are graded by both the Gemological Institute of America and GemEx, to guarantee their quality and ensure that they have unmatched sparkle, fire, and brilliance.