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Diamond Certification

Also referred to as a diamond grading report, diamond dossier or diamond quality document, the certificate contains a detailed analysis of the diamond’s size, cut, colour, clarity, florescence, finish and other relevant characteristics.

Certification Bodies

An international standard for diamond grading does not exist, so, somewhat confusingly, you’ll find that different labs use different processes and techniques when testing the stones for quality and may produce a different set of results if asked to grade the same stone.

The major certification labs include:

  • The GIA (Gemological Institute of America) is generally considered to be very reliable and their standards and terminology are the closest there is to an international consensus. Certificates from GIA labs can be 3-4% more expensive than those obtained elsewhere.
  • AGSL (American Gem Society Laboratories): This highly respected organisation ranks cut, colour, and clarity on a simple scale of zero to ten, with zero describing the rarest and most desirable diamonds, and ten indicating the least desirable.
  • BGI (British Gemmological Institute): Situated in London the BGI was established in 1931 and offers reliable, accurate grading.
  • DPL (Diamond Profile Laboratory): This more recently established lab is keen on exploring new technology in its grading processes. An added feature of certificates obtained from DPL is a set of digital photos of each stone.
  • GEM A (Gem Testing Laboratory of Great Britain): Reports from this lab are based on the principles of “harmonized grading” for colour and clarity of diamonds and provide all the essential information you will need. This is also the only laboratory in the UK registered by CIBJO to issue CIBJO Diamond Grading Reports.
  • HRD (Diamond High Council): This lab is based in Antwerp, Belgium where it is highly regarded. Most European labs have been influenced by the methods used by the GIA.
  • IGI (International Gemmological Institute): Established in 1975 in Antwerp with a network of labs in a number of different countries.
  • PSL (Precious Stone Laboratory): Another London-based lab, you will often find PSL listed among the more reliable graders.
  • EGL (European Gemmological Laboratories): A network of labs with centres in a number of different countries.

Second hand diamonds may also come with certificates from a wide variety of labs.

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