Under Responsible Jewellery Council Guidelines:

• A wholly or partially Synthetic diamond must always be disclosed as “laboratory created”, “laboratory grown”, “man-made”, “[Manufacturer’s name] created”, and/or “Synthetic” and the description must be equally as conspicuous and immediately preceding the word “diamond”.
• Members will not use the words “real”, “genuine” or “natural” to describe any Synthetic, or any terms that may disguise the fact that a diamond is Synthetic or that mislead the consumer in any way.

For further information please refer to the following link:

http://www.responsiblejewellery.com/downloads/S001_2008_RJC_Prin_COP.pdf

Under Federal Trade Commission Guidelines:

§ 23.23 Misuse of the words "ruby," "sapphire," "emerald," "topaz," "stone," "birthstone," "gemstone," etc.

• (a) It is unfair or deceptive to use the unqualified words "ruby," "sapphire," "emerald," "topaz," or the name of any other precious or semi-precious stone to describe any product that is not in fact a natural stone of the type described. 
• (b) It is unfair or deceptive to use the word "ruby," "sapphire," "emerald," "topaz," or the name of any other precious or semi-precious stone, or the word "stone," "birthstone," "gemstone,'' or similar term to describe a laboratory-grown, laboratory-created, [manufacturer name]-created, synthetic, imitation, or simulated stone, unless such word or name is immediately preceded with equal conspicuousness by the word "laboratory-grown," "laboratory-created," "[manufacturer name]-created," "synthetic," or by the word "imitation" or "simulated," so as to disclose clearly the nature of the product and the fact it is not a natural gemstone.
• Note to paragraph (b):  The use of the word "faux" to describe a laboratory-created or imitation stone is not an adequate disclosure that the stone is not natural.
• It is unfair or deceptive to use the word "laboratory-grown," "laboratory-created," "[manufacturer name]-created," or "synthetic" with the name of any natural stone to describe any industry product unless such industry product has essentially the same optical, physical, and chemical properties as the stone named.

§ 23.24 Misuse of the words "real," "genuine," "natural," "precious," etc.

• It is unfair or deceptive to use the word "real," "genuine," "natural," "precious," "semi-precious," or similar terms to describe any industry product that is manufactured or produced artificially.

For further information please refer to the following link:

http://www.ftc.gov/bcp/guides/jewel-gd.shtm

CEN, the European Committee for Standardisation, Workshop Agreement 15965:2009 (CWA) - ‘Consumer Confidence and Diamond Nomenclature’

De Beers was recently involved in an important cross-industry procedure to produce clear diamond terminology to maintain consumer confidence in diamonds.

The 'CEN Workshop Agreement 15965:2009 (CWA) on Consumer Confidence and Diamond Nomenclature' is a cross-industry agreement that was created within the bounds of a framework provided by CEN, the European Committee for Standardisation.

The CWA was formally published by CEN in May 2009 following an agreement by consensus amongst participants at a public meeting in Antwerp/st1 :city> on 19 November 2008.

The CWA was made up of a wide range of participants including representatives of mining companies, African producer country embassies, producers of synthetic diamonds, gemmological associations, retailers and grading laboratories.

The aim of this CWA is to provide a clear set of nomenclature on diamonds for consumers so that they continue to be informed when they are making diamond purchases.  The CWA process was designed to be flexible to allow a consensus to be reached and permitted the following words to be used to describe synthetic diamonds: “laboratory created", “laboratory grown” or  “synthetic”.

The word ‘’diamond’’ or ‘’natural diamond’’ alone can only be used for the description of natural diamonds.

Disclosure of synthetic diamonds now has to be ‘’immediately apparent and unambiguous’’ to the customer. This is in line with the International Diamond Council and Responsible Jewellery Council’s guidelines on diamond terminology. 

The Workshop Agreement is not designed to compete with existing guidance documents and is a voluntary agreement.  The text of this CWA was based on the CIBJO 2006 Diamond Book and the 2008 IDC rules for grading polished diamonds, 3rd edition 2008.

The CWA does not have any impact on existing industry standards or existing national legislation and does not place diamond manufacturers under any legal obligation to abide by the text agreed within the Workshop.

De Beers recognises the importance of ensuring that diamonds are clearly described and that consumers are aware of exactly what products they are buying. In this respect, De Beers supports the CEN Workshop Agreement and welcomes the fact that such a wide range of organisations and individuals were able to agree on a robust set of guidelines for diamond nomenclature.