Diamonds Grading Labs

Diamonds Index

Round Brilliant Cut Diamond

• Testing Gemstones
  Primarily to identify them, but also to ensure they are natural and whether they have been treated. This can include diamonds.
• Grading Diamonds
  And providing independent certification of their quality.

Diamond Grading Laboratories

• GIA - Gemmological Institute of America
  The GIA is internationally recognised. Its terminology and standards have become almost a de facto international standard.
  
• CIBJO - Confederation International de la Bijouterie, Joaillerie, Orfevrerie des Diamantes, Perles at Pierres.
  This translates as "International Confederation of Jewellery, Silverware, Diamonds, Pearls and Stones", which is quite a mouthful in any language! CIBJO has about 95 members in 27 countries, although not all of these operate a diamond laboratory. There are 14 CIBJO labs in 12 countries. Some of these labs are specialised in that they do not offer expertise in all branches of gemmology. It is interesting to note that the GIA is listed as a member of CIBJO.
• GAGTL - The Gemmological Association and Gem Testing Laboratory of Great Britain
  Otherwise known as the London Gem Lab, the Gem Lab used to be operated by the London County Council. The GAGTL is a member of CIBJO.
• Other Laboratories
  There are many other laboratories throughout the world, some may be very accurate and conscientious, but not all can be relied upon to provide first class, honest, and reliable grading. Indeed in most countries anybody could, and often does, set up as a gemmological grading laboratory, offering cut-price grading certificates to dealers, manufacturers, and retailers of all ethical persuasions.
  Many diamond grading certificates are probably not worth the paper they are written on!
• Retailer Certificates
  While these may be better than nothing at all, it is worth asking a few searching questions before accepting a retailer's, or any other trader's diamond grading certificate. A few sample questions could include:-
  
  • Who has graded the diamonds?
  • What are his / her qualifications?
  • What guarantee of accuracy is there?
  • Is the grading / certification part of the purchase contract?
  We take the view that a trader's grading, (including our own!), is less likely to be as accurate and objective as that from a recognised laboratory. Some traders' grading will be less reliable than others.

Diamonds - Technical Data
Diamonds - Certification
Diamonds - The 4 C's
Gemstone Information

Diamond Glossary - An A to Z of Diamonds