Diamond Frequently Asked Questions

Diamond Cut

How is cut measured?




What's the difference between Ideal Cut and Astor Ideal Cut in round diamonds?

While both cuts are of a very high quality, Astor by Blue Nile™ diamonds are cut to gather and reflect the most light possible. They are graded by both the Gemological Institute of America - the world's most respected independent laboratory, and GemEx - the leader in light measurement, to guarantee their uncommon brilliance.

What are polish and symmetry? How do they affect sparkle?


Diamond Color

What is fluorescence and how does it affect the color of a diamond?


What are "colored diamonds" and does Blue Nile offer them?

Colored diamonds are an extremely rare, natural phenomenon of nature. If, while diamonds are being created deep inside the earth, they are exposed to certain trace elements, the result can be a colored diamond in almost any hue of the rainbow. All Blue Nile colored diamonds possess natural color and are never exposed to artificial coloring techniques such as dyeing or irradiation. As with all Blue Nile loose diamonds, each colored diamond is accompanied by a Gemological Institute of America (GIA) report, which lists the diamond's specifications (e.g. color grade) and natural origin.

Does clarity grade affect a diamond's sparkle and brilliance?



For a three-stone ring, Blue Nile recommends that you choose the same cut grade for each of the diamonds, but color and/or clarity can differ. For color, there will not be a visible difference within three grades. For example, D, E, and F will each look the same. For clarity, anything VS2 or above will appear the same.

Diamond Certification

What is the difference between the AGSL and the GIA certificates?



The International Gemological Institute (IGI) and the European Gemological Laboratory (EGL) are two other independent diamond grading laboratories. Blue Nile does not carry diamonds certified by these laboratories.

What is a GemEx Diamond Light Performance Certificate?

With the GemEx Certificate, you know how your diamond performs. Each and every diamond has been scientifically measured for its Light Performance certificate. The five diamond images on the front of the certificate are the actual images of the diamond that you own or are going to purchase. These images from the BrillianceScope are used to evaluate the percentage of white light and color light that the diamond returns and the number of points of light that turn on and off as the diamond moves. GemEx ensures accurate brilliance, fire and sparkle results by measuring every diamond at multiple light angles. The bar graphs show how your diamond compares to all others in the world in each category (i.e. Round or Princess cuts). GemEx developed the scales for each shape by measuring tens of thousands of diamond to determine the range of brilliance, fire and sparkle possible. The IdentiView image reveals the craftsmanship and symmetry of the diamond. Learn more about the GemEx Diamond Light Performance Certificate here.

Does Blue Nile offer an appraisal for my jewelry purchase?

Yes. An appraisal accompanies all diamond engagement rings, any jewelry set using our Build Your Own Diamond Jewelry® feature, and most other jewelry over $1,000.