The Diamond Commission of CIBJO, the World Jewellery Confederation, has been working to refine the definitions of "natural" and "synthetic" diamonds that appear in the Diamond Blue Book manual for the diamond trade.

In a special report released ahead of the 2011 CIBJO Congress in Porto, Portugal, the Diamond Commission proposes changes to the text of the Diamond Book – regarded as a "living document" that must be updated in accordance with changes in the industry and the market – that include prohibiting the use of the following words to describe any synthetic diamond: real, genuine, gemstone, natural, cultured, or cultivated. The terms "cultured" and "cultivated" are recommended for use in describing pearls only.

Gerard Grospiron, a CIBJO delegate from France, has proposed fine-tuning the definition of "natural diamond" to a diamond formed entirely by nature and unmodified by humans except for cutting and polishing.

According to CIBJO, its Diamond Commission's work on the issue brings the organization's nomenclature for synthetic diamonds "mostly in sync" with that of the International Diamond Council.