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Diamond Education

The 4Cs of Diamonds

This short tutorial explains the 4Cs of Diamonds - cut, colour, clarity, and carat weight - the most important characteristics to understand when making a diamond purchase.

Diamond Cut


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

Learn More About Cut

Diamond Colour


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

Diamond Clarity


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

Learn More About Clarity

Diamond Carat


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

Learn More About Carat

Diamond Shape


Each diamond shape has different attributes that affect price and quality grade.

Learn More About Shape

Diamond Certification


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

Learn More About Certification


As the largest online diamond retailer, Blue Nile offers the largest collection of the world's finest cut diamonds. Pre-selected for exceptional quality, the cut, colour, and clarity of our loose diamonds are evaluated based on a standardized grading scale. Also, each loose diamond is accompanied by a grading report from either GIA, AGSL, or GemEx, independent diamond grading labs with stringent grading and certification guidelines.

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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