This buying guide provides a quick overview of the quality factors to keep in mind when shopping for a diamond. Blue Nile will help you find the right diamond by first helping you understand what makes a diamond the right one.
The first step is to ensure your diamond is certified. A diamond certificate is proof that a diamond has been analyzed by an unbiased team of gemologists. At Blue Nile, you can use our interactive diamond search to choose from thousands of diamonds certified by the two most respected independent diamond labs, the GIA or AGSL. All certified diamonds are graded based on the four Cs: cut, color, clarity, and carat weight.

Cut: The diamond’s cut determines its fire and brilliance. Cut grade is established by defining the relationship between a diamond’s light performance, dimensions, and finish. Even with exceptional color and clarity, if a diamond is poorly cut, it will look dull. Choose a good, very good, or ideal cut grade.

Color: Diamonds are graded based on the presence or absence of color. Diamonds with less color have a better grade and will display more colorful fire. A diamond with a color grade of D, E, or F is regarded as colorless. Color grades of G, H, I, and J are considered near-colorless, and can offer excellent values.

Clarity: Trained gemologists use strict guidelines to summarize and map the flaws, or inclusions, in a diamond. While diamonds with flawless clarity are rare and expensive, a diamond with no flaws visible to the unaided eye, referred to as eye-clean, can offer outstanding value without sacrificing brilliance. Choose VS1 or VS2 grades or better. Learn more.

Carat Weight: Carat is a measure of weight, not size, and two diamonds with the same carat weight but different cut characteristics will not appear to be the same size when viewed from the top. Also, in general, it takes about a 20% increase in carat weight before most people will notice a difference in size.

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