Diamond Education

The 4Cs of Diamonds

This short tutorial explains the 4Cs - cut, colour, clarity, and carat weight - the most important characteristics of buying a diamond.


The most important of the 4Cs is Cut because it has the greatest influence on a diamond's sparkle.

Learn More About Cut


The second most important of the 4Cs is Colour, which refers to a diamond's lack of colour. The less colour, the higher the grade.

Learn More About Colour


Often the least important of the 4Cs because the tiny imperfections are often microscopic.

Learn More About Clarity


The term Carat actually refers to the diamond's total weight and not its size.

Learn More About Carat


Each Fancy Shape has different attributes that affect price and quality grade.

Learn More About Shape


Unbiased diamond grading reports are offered with every Blue Nile diamond.

Learn More About Certification


As one of the largest online diamond retailers, Blue Nile offers a huge selection of the world's finest diamonds, pre-selected for exceptional quality, cut, colour, and clarity based on a standardized grading scale. Each loose diamond is accompanied by a grading report from the GIA, a respected, independent diamond grading lab with extremely stringent grading scales.

Blue Nile Standards Chart

Price Match Guarantee

If you find a comparable GIA graded diamond at a lower price, we'll review to match the price.

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Diamond Upgrade Program

We offer a lifetime diamond upgrade program on all GIA and AGSL graded diamonds.

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Conflict Free Diamonds

Blue Nile diamonds are ethically sourced with a zero-tolerance policy for conflict diamonds.

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What Our Customers Chose

Visit our recently purchased rings and see the engagement rings other customers have recently chosen