Gemstones, diamonds, as well as pearls and corals are natural materials that have been created without human intervention. However, due to their rarity and beauty, there are numerous treatment methods to optimize these materials. Furthermore, humans are able to produce synthetic gemstones (man-made stones with the same physical and chemical properties as their natural counterparts, e.g. synthetic ruby) and artificial products (without a natural counterpart, e.g. cubic zirconia).

In order to ensure transparency in trade and to protect customers, there is the “International Association for Jewellery, Silverware, Diamonds, Pearls and Stones”, CIBJO for short (abbreviation from French). This trade organization endeavors to harmonize and standardize the declaration provisions that are specified in the individual CIBJO Blue Books. This is to ensure that each product is correctly labeled and offered unequivocally and without ambiguity.

Gemstones can be subjected to a wide variety of treatments to change their colour, transparency and stability. In the CIBJO Blue Books, a distinction is made between a general and a specific disclosure requirement for treatments. Treatments that require public disclosure include: heating, crack-filling with colorless organic substances (oil, resin, polymers, or wax), and superficial waxing and bleaching. These treatments require verbal disclosure in plain language prior to or at the close of the sale and should be detailed in commercial documents. In the case of treatments with a specific disclosure obligation, a full written disclosure must be made on the business documents in addition to an oral explanation. These include: coloring with dyes, coatings and coatings, irradiation, filling of cracks and cavities, diffusion treatments, laser drilling, and impregnation/stabilization.

To protect trade and customers, a large number of gemstones are offered with an additional gemological report (by an independent laboratory) which, in addition to the identity, also lists any treatments detected. At this point, the “Laboratory Manual Harmonization Committee”, LMHC for short, should be mentioned, a committee consisting of various gemmological laboratories with the intention of creating a standard for a uniform nomenclature. These include the GIA (Gemological Institute of America), DSEF (German Foundation for Gemstone Research in Idar-Oberstein), as well as the SSEF (Swiss Foundation for Gemstone Research) and Gübelin Gem Lab in Switzerland. Detailed explanations of treatments and terminology used in LMHC members’ gemological reports are set out on their respective LMHC factsheets.

For complete information on this subject, consult the individual CIBJO blue books and LMHC information sheets.