HRD Diamond Grading Standards
Diamonds are analyzed by several expert gemologists using state-of-the-art laboratory equipment. Many gemologists must agree on the collective quality of a diamond before a grading consensus is reached. To ensure adherence to stringent standards, senior gemologists randomly monitor grading results for accuracy and consistency.
- A Diamond's Origin
- The origin of the diamond is determined through thorough investigation, and steps are taken to certify the stone as a natural diamond.
- Diamond Carat
- A diamond's carat weight is measured using carefully calibrated gemstone scales, and is noted up to the fifth decimal. The diamond's measurements are taken and fluorescence, if any, is described.
- Diamond Color
- The color of a diamond is graded on a scale ranging from Exceptional White to Tinted Color. The GIA's D to Z equivalent is noted as well.
- Diamond Clarity
- Clarity is determined on a grading scale ranging from Loupe Clean (flawless) to P3 (imperfect) based on the number, size, brightness, and location of internal and external characteristics. Any detected inclusions are plotted on a diagram.
- Diamond Proportions
- The proportions, or cut grade, of a diamond are determined as Very Good, Good, or Unusual based on a combination of the stone's girdle thickness, culet, table width, crown height, and pavilion depth.
- Finish Grade
- A diamond's Finish Grade is determined on a scale ranging from Very Good to Poor. This rating is based on the quality of the workmanship of the diamond polisher.