Diamond Education

The 4Cs of Diamonds

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

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Cut

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

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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

Clarity

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

Learn More About Clarity

Carat Weight

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

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Shape

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

Learn More About Shape

Certification

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

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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.

Chart displaying the Cut, Colour, and Clarity grades carried by Blue Nile compared to low quality grades not carried by Blue Nile.

Grade	Not Carried by Blue Nile	Blue Nile Quality
Cut	Fair and Poor	Good, Very Good, Ideal, and Astor Ideal
Colour	L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, and Z	K, J, I, H, G, F, E, and D
Clarity	I1, I2, and I3	SI2, SI1, VS2, VS1, VVS2, VVS1, IF, and FL