Get Our Diamond-Buying Cheat Sheet  | Sign Up for Our Emails Now

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.

find your diamond


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