What is a Diamond Certificate?

A diamond certificate is the official "finger print" of a diamond graded by an accredited gemological laboratory. These reports are the most accurate way to determine the quality of a diamond.

The purpose of a diamond certificate is to analyze and put down in writing the specific characteristics of a diamond. It includes: dimensions, carat weight, clarity and color, cut grade and inclusions.

Which Diamonds Have Certificates?

Only loose diamonds, meaning those not yet set or removed from the setting, are able to be certified by GIA. To ensure objectivity, diamonds are graded by multiple experts separately, and free of any identification that could skew their opinion. It is unusual to see diamond under 0.50 carat submitted for grading due to the time-intensive and expensive nature of this process.

Why Are Certificates Important?

Diamonds graded by the same agency can be compared on identical standards and measurements. This fair scale is the best way to determine a diamond's market value, especially since small variations in quality can translate into huge monetary differences.

Are All Diamond Certificates the Same?

Wonder Jewelers offers diamonds with certificates from one of the following independent accredited laboratories:

  • American Gemological Society (AGS)
  • Gemological Institute of America (GIA)
  • European Gemological Laboratories (EGL)

These are the 3 most well respected labs and vary slightly in grading standards. In general, AGS and GIA are considered to be the most conservative than the EGL. So, a diamond with a GIA or AGS certificate will usually cost a few percent more than a similar EGL certified diamond.

Here at Wonder Jewelers, we strongly believe in a policy of 100% transparency. We are always honest about a diamond's certificate and are experts at navigating their minute differences to get you the best value.

What's on a diamond certificate?

  • Laboratory certificates contain a standard set of grades, weights and measurements:
  • Cut: diamond shape and style, e.g., round brilliant cut
  • Dimensions: measurements of the diamond in millimeters, e.g. 6.49 - 6.51 x 3.80 is the smallest - largest diameter and the total depth of a round brilliant diamond
  • Carat: weight of the diamond to the nearest hundredth of a carat
  • Proportions: Depth % (round diamonds) and Table % (round diamonds): in proportion to the diameter
  • Girdle: range of girdle thickness, e.g. thin to medium
  • Culet: appearance of the culet facet, e.g., very small
  • Finish: Grades for polish and grades for symmetry ranging from poor to excellent
  • Clarity: clarity of the diamond from under 10X magnification
  • Clarity Plot: a diagram of the approximate size, location, and type of inclusions as through a microscope
  • Color: color grade, usually the GIA 'D-Z' scale
  • Fluorescence: color and strength of fluorescence when the diamond is exposed to UV light
  • Comments: additional relevant information not mentioned elsewhere in the report

This sample certificate is from GIA:

What is the Difference Between a Certificate and An Appraisal

A Certificate lists the physical characteristics of a diamond that will determine its market value. It does not purport to provide the actual monetary value. An appraisal uses a certificate to provide as accurate a market value for the diamond as possible.