Diamond Certificate

Diamond Grading

A diamond grading report is a source of evidence that provides a summary of the characteristics of a diamond which will establish its value; it provides an authoritative analysis of your diamond.

Diamond grading reports are carried out by highly trained and qualified professional gemologists. These grading reports are established using high-quality gemological equipment, where a diamond is evaluated, measured, and scrutinised using trained eyes, a jeweller's loupe, a microscope, and other industry tools. Diamond grading certificates include an analysis of the diamond's dimensions, clarity, colour, polish, symmetry, and other characteristics. When referring to round diamonds a report may also include a cut grade.

At Ziba and Co we offer a variety of diamond grading reports; below are some of the most respected laboratories in the diamond industry which we stand by. Diamonds which are accompanied by a diamond grading certificate are the most highly valued in the industry.

  • GIA: Gemological Institute of America
  • IGL: International Gemological Laboratory
  • IGI: International Gemological Institute
  • AGS: American Gem Society
  • HRD: HRD Antwerp, Institution of Gemmology

GIA: Gemological Institute of America


The Gemological Institute of America (GIA) was established in 1931, it is the largest most respected non-profit institute of gemological research and education. A diamond grading report signifies a blueprint of your stone and provides exact qualities. An analysis of a diamonds characteristic is provided on the grading report based on the (4C's) cut, colour, clarity, and carat. Additional grading information is also provided like the polish, symmetry and fluorescence. GIA also provides a profile about the exact proportions of your diamond whilst including the clarity characteristics.

IGL: International Gemological Laboratory


International Gemological Laboratory provides a reliable and accurate documentation of a diamond's identity and grade. All diamonds are analysed by gemologists that provide an accurate description of the analysis of the diamond. The characteristics of a diamond include the 4C's.

IGI: International Gemological Institute


The International Gemological Institute (IGI) was established in 1975, it is the eldest and first laboratory that issues jewellery identification reports with a high-quality diamond cut grading chart.

IGI is the largest organisation of its kind; it brings the fifth 'C' that is often missed: Confidence. The International Gemological Institute (IGI) focuses on consumer concerns and understanding.

AGS: American Gem Society


The American Gem Society (AGS) was founded in 1934; it is a small group of professional jewellers. They focus on protecting their consumers/clients towards purchasing falsely advertised items, to ensure the best quality diamonds and gemstones are provided.

With purchases from the American Gem Society (AGS) comes a diamond quality report that provides informative data about your diamond. The information given provides the 4C's, commentary details about the fluorescence and a grading scale which illustrates where each diamond stands.

HRD: HRD Antwerp, Institution of Gemmology


HRD was established in 1973, they have the most reliable diamond grading report which dedicates them to delivering the perfect diamond to their customers. HRD grading reports have charts on all sizes and shapes of diamonds including coloured or fancy cut diamonds. The diamond grading chart includes the 4C's, colour grading scale, cut grading scale, technical information about the measurements of the diamond and laser inscription.