One of the rarest colors of diamond, blue also ranks among the most desired. Like the famous Hope Diamond, these blue gems will make stunning showcase stones in any jewelry piece. However, most blue diamonds exhibit grey hues and can never reach the saturation of top-grade blue sapphires. While the high price of naturally beautiful blue diamonds continues to rise, treated and created gems give buyers an affordable alternative to these collector’s pieces. Most gem enthusiasts understand the four Cs of colorless diamonds, but the quality factors for fancy colored blue diamonds remain less familiar. Our blue diamond buying guide will help consumers understand them.

Fancy Colored Blue Diamond Buying and the Four Cs

The IGS colored diamond value listing has price guidelines for irradiated blue diamonds.

Color

Unlike colorless diamonds, where cut ranks above color, clarity, and carat, a fancy colored blue diamond’s value comes primarily from its color. Hue, tone, and saturation are the three constituent components of gemstone color.

For a fancy colored blue diamond, the primary hue is blue. Green or, more rarely, purple secondary hues may be present. While neither is desirable, gems with greenish hues hold more value than those with a…