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 Gemmological 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 Colour



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

Coloured 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 coloured diamond in almost any hue of the rainbow. All Blue Nile coloured diamonds possess natural colour and are never exposed to artificial coloring techniques such as dyeing or irradiation. As with all Blue Nile loose diamonds, each coloured diamond is accompanied by a Gemmological Institute of America (GIA) report, which lists the diamond's specifications (e.g. colour grade) and natural origin.

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


For a three-stone ring, should you keep the same color/cut/clarity parameters for the side diamonds?


Diamond Certification

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




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 colour 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 jewellery purchase?

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