In the late 1960s and early 1970s, the leadership of the international diamond industry’s two leading representative organisations, the World Federation of Diamond Bourses (WFDB) and the International Diamond ManufacturersAssociation (IDMA), recognised that the number of private labs grading diamonds was exploding, and each seemed to be claiming that its standards were the best and its results the most reliable. A body of opinion developed, therefore, that it was time for the WFDB and IDMA to take matters into their own hands. Therefore, during the World Diamond Congress in Amsterdam in 1975, a Joint Committee of the WFDB and IDMA was set up, which was later renamed the International Diamond Council (IDC).

Experienced diamond cutters and dealers from Amsterdam, Antwerp, Idar-Oberstein, Johannesburg and Ramat Gan were asked to work out reliable and clear "guidelines for grading polished diamonds." This committee presented itsproposals, called the “International Rules for Grading Polished Diamonds,” to the World Diamond Congress in Tel Aviv in 1978, and they were unanimously approved. In 1980, the U.S. representatives changed their approval to an abstention.

Initially, three labs fully adopted these standards and complied with them: the Diamond Lab of HRD Antwerp, the Jewellery Council of South Africa in Johannesburg, and the Diamant Prüflabor (DPL) in Idar-Oberstein. Needlessto say, the above mentioned labs and especially HRD Antwerp carried out the research to develop and update the IDC rules.

Since 1975, many positive developments have occurred, among the most significant being accreditation by the International Standards Organisation (ISO). Initially, the HRD Diamond Lab of HRD Antwerp and then the Diamant Prüflabor (DPL) were the only labs whose standards of quality management for grading polished diamonds were ISO accredited, but others have followed suit and the trend continues.

The IDC rules were revised slightly in 1995, and the changes were accepted by the WFDB and the IDMA. In November 2005, the IDC presented an updated survey regarding definitions and nomenclature at the WFDB and IDMA Presidents’ Meeting in Mumbai. Both organizations accepted all the proposals, but the IDMA voted in favour of allowing gem labs to issue grading reports for synthetic diamonds, while the WFDB refused to do so. However, this sensitive issue has since been resolved.

The latest revision of the IDC Rules was presented and approved by the WFDB and IDMA at the 33rd World Diamond Congress, held in May 2008 in Shanghai, China. Since 2008, the IDC Rules have undergone minor modifications andupdates. More importantly, translations of the rules have become available in Arabic, Chinese, German and Russian! It is important, however, to note that the latest English version is the authoritative text. It is expected that the last version of the IDC rules will be tabled for approval at the 37th World Diamond Congress to be held in Dubai, in Spring 2016.

Meanwhile, IDC and CIBJO, The World Jewellery Confederation, have reached agreement on the adoption of a unified, single standard for the nomenclature of synthetic, gem-quality diamonds. Therefore, since IDC and CIBJO now see eye to eye on all diamond nomenclature and grading standards issues, a working group of IDC officers and the CIBJO Diamond Commission are currently preparing for the amalgamation of the IDC Rules and the CIBJO Diamond Book into a single entity.

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