• Dec 19, 2018
  • by Robert Kohler



A diamond’s value is based on four criteria:

  • Color often is graded on a scale established by the Gemological Institute of America (GIA). On the GIA scales, color is rated from D to Z, with D at the top.
  • Cut refers to the quality of how the diamond has been shaped, taking into account the diamond’s proportions, polish, and symmetry.
  • Clarity measures the natural imperfections in the stone. On the GIA scales, clarity is rated from flawless to I3. A diamond can be described as “flawless” only if it has no visible surface or internal imperfections when viewed under 10-power magnification by a skilled diamond grader.
  • Carat refers to the stone’s weight.

Diamond weight usually is stated in carats and may be described in decimal or fractional parts of a carat. If the weight is given in decimal parts of a carat, the figure should be accurate to the last decimal place. For example, ”.30 carat” could represent a diamond that weighs between .295 and .304 carat. Some retailers describe diamond weight in fractions, using the fraction to represent a range of weights. A diamond described as 1/2 carat could weigh between .47 and .54 carat. If diamond weight is stated as fractional parts of a carat, the retailer should disclose two things:

  • that the weight is not exact
  • the reasonable range of weight for each fraction or the weight tolerance being used