tweezers holding a diamond

The most important factor of all is to trust the company from which you are buying. You should be confident that whatever you are buying is accurately presented to you, and the company should stand behind its grading whether the item has a certificate or not. The company should provide a written verification of your purchase that includes an accurate description of the item and the replacement value (appraisal). Make sure if the company is a verified Member of the Better Business Bureau in the city that it is located. The seal of the BBB should be displayed on the website or in the business.

Remember that diamond certificates are not guarantees, valuations or appraisals. While professional labs employ experienced well-trained graders and use the most accurate gemological instruments to grade gemstones, laboratories make no warranties regarding the accuracy of their certificates. Diamond grading, like diamond cutting, is both an art and a science.Take the time to understand how to read a certificate, however, your diamond purchase should not be based solely on this document. It cannot replace a visual inspection of the diamond you are considering. Some diamonds are beautiful even if they don’t look good on paper.

Unique ID Number

The certificate will have its own identification number.


Look for a statement attesting the origin, i.e., whether it is a natural diamond or it has been enhanced. Labs do not grade fracture-filled diamonds.

Carat Weight

Shape, such as round, pear or oval, and cutting style, such as brilliant or step cut, are noted on a certificate.


Major laboratories measure diamonds in millimeters, typically to the hundredth of a millimeter. Exact dimensions are very important in identifying a diamond, as it is unlikely that two diamonds will have identical weight and dimensions.

Shape and Cut

When diamonds first began to be given as engagement rings, settings were elaborate and did not necessarily showcase the diamond in its best light. It actually wasn’t until the discovery of diamond mines on the African continent in 1870 that diamonds became accessible to a wider public, increasing demand and influencing design. Subsequently, diamond jewelry began to be designed to demonstrate the unique beauty and brilliance of diamonds.


Good proportion–particularly the depth and table percentages–influences the brilliance and fire of a diamond. In fact, proportion is as important as color and clarity grades.

Clarity and Color Grades

Most diamond buyers know their 4Cs: cut, color, clarity, and carat weight.


Some diamonds will appear to exhibit different colors in ultraviolet light. This property is called fluorescence.