Certified Diamonds

Certified diamonds are loose diamonds that have been graded by a gemological laboratory based on their "4 C" attributes Cut, Color, Clarity, and Carat Weight. Although today's diamond grading techniques are more sophisticated and standardized, early evaluation of diamonds was fairly rudimentary. The London Diamond Syndicate, formed in 1890 as a collaborative organization between buyers and sellers for diamonds extracted from De Beers mines, utilized a loose color grading system as a means of sorting through rough diamonds. Early grading systems lacked consistency, often using vague terms like 'fine white' or 'brown' to describe diamond color.

In 1931, former jewelry retailer Robert M. Shipley established the Gemological Institute of America (GIA) in an effort to educate the jewelry industry through research and gemological instrumentation. Initially, the GIA was based in Shipley's home, providing gem-testing services and mail-order courses. The Institute continued to grow, acquiring specialized equipment and honing testing techniques, and by 1953, developed the 4 Cs as well as the GIA International Diamond Grading System to objectively compare and evaluate loose diamonds. Today, certified diamonds are graded based on the internationally accepted standards set forth by the GIA.

Graded Characteristics of Certified Diamonds

The carat weight of diamonds is measured on electronic microbalances, recorded with precise measurements to the fifth (ten-thousandth) decimal place. The color of a certified diamond is graded against master stones of predetermined color in a standardized viewing element under controlled lighting and backgrounds. Microscopes with 10X magnification are used to examine diamonds for the presence of inclusions and blemishes. During clarity grading, evaluators also screen the stone to determine if it's synthetic, and will look for signs of diamond alteration, such as fracture filling or color enhancement. It's a common misconception that diamond cut refers solely to the stone's shape. However, this characteristic is actually a measure of its proportions, polish, symmetry, facet uniformity, and polish. A diamond's certificate will also include basic information like shape, measurements, and fluorescence (a measure of the diamond's reaction to UV light).

Why Buy Certified Diamonds?

Certified diamonds have been verified for quality, allowing consumers to purchase with confidence based on the attributes of the diamond rather than blindly trusting the sales pitch of the retailer. When armed with a grading certificate, consumers have a pretty good idea of what the diamond will look like without having to see it in person. Certified diamonds also:

  • Hold their value better than their non-certified counterparts, especially for resale and upgrading purposes
  • Simplify the comparison process"it's much easier to compare certified diamonds based on the 4 Cs than it is to rely on visual inspection alone
  • Broaden the shopping base to include online retailers, resulting in significant savings

When purchasing certified diamonds, be sure the diamond certification is from a third-party laboratory rather than one associated with the store, jeweler, or diamond wholesaler, who may offer a biased opinion to facilitate the sale. Also, verify that the third-party laboratory has a history of stringent grading practices and that they've been in business long enough to establish a solid reputation in the jewelry industry. Brilliance recommends the following laboratories, in order of preference: GIA, AGS, EGL, IGI, and HRD.

Diamond Certificate vs. Diamond Appraisal

In addition, some retailers will try to pass off a diamond appraisal as a diamond certificate, when there is actually a significant difference between the two documents. A diamond appraisal is typically prepared by the seller of the diamond to denote the estimated value for insurance purposes, while a diamond certificate is an unbiased analysis of the stone's quality prepared by a gemological laboratory.

What to Look For When Purchasing Certified Diamonds

Diamonds Shape

Diamond Shape

Choose a shape that flatters your hand and complements your personal style. Round diamonds exceed all other shapes in their ability to reflect light. Learn about diamond shape.

Diamonds Carat Weight

Carat Weight

Look for the largest size within your price range that is still good quality. Don't sacrifice quality for size; remember, bigger isn't necessarily better. Learn about diamond diamond carat.

Diamonds Color

Diamond Color

The less color, the better. Diamonds are color graded on a scale from D-Z, with D as the most desirable (and valuable). Learn about diamond color.

Diamonds Cut

Diamond Cut

A diamond's cut is graded on a scale from Excellent/Ideal - Poor; the better the cut grade, the more brilliance the diamond will emit. Learn about diamond cut.

Diamonds Clarity

Diamond Clarity

While flawless is best, inclusions make up the 'fingerprint' of the diamond. Look for inclusions that are not noticeable to the naked eye. The grading scale ranges from FL - I3. Learn about diamond clarity.

Diamond Fluorescence


Diamond fluorescence, is graded from None to Very Strong. Though fluorescence doesn't usually affect the diamond's quality, it's best to look for grades of Medium, Faint, or None.