Over 99% of emeralds have surface reaching fractures that are treated with oil, wax, resin, or something else entirely. This is done to improve the clarity of emeralds, and usually termed as enhancement instead of treatment is the sales sector of the gem industry. Labs will instead use terms such as treatment. The American Gem Trade Association (AGTA) has defined an enhancement as: Any traditional process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.
Fracture filling in emeralds is a very old practice. In the case of oiling a high viscosity cedar oil is typically used, though there are alternatives. Anything that has a similar refractive index to emeralds, meaning light passes through the materials similarly.
Oil treatments are not necessarily permanent and stable. Time, heat, or improper cleaning, will cause the oil to evaporate, change color, or leach out of the stone. This is not a problem because emeralds can be re-oiled if the oil is accidentally removed or it has become discolored.
Natural and synthetic resins are alternatives to oil because they do not dry out as quickly. Natural resins such as Canadian balsam as well as manufactured resins and polymers including Opticon, ExCel, and Permasafe, are more durable and last longer than oil. The caveat to this treatment is that it is nearly impossible to clean out the resin afterwards. Especially if a hardener (also called a plasticizer or stabilizer) was added to prolong the longevity of the treatment.
Fracture filling is typically performed on emeralds after they have been cut. A new technique applies what is essentially glue to the emerald rough beforehand, then cuts the emeralds afterwards.
The caveat of these emeralds is that the glue eventually dries out and these emeralds fall apart. Most gem dealers do not carry these types of emeralds, as they constitute as a manufactured emerald since they could never be cut without the glue. This practice is widely frowned upon in the industry, though if someone is willing to buy these emeralds for what they are that is a separate story.
Colored oil is used to improve the apparent color of some emeralds and green beryl although the practice is generally frowned upon. However, all treatments for gems are fine so long as this information is disclosed to the customer. This also means appropriate pricing, and informing the customer on how to properly care for emeralds with these treatments too. Lack of disclosure for any of these factors is fraudulent.
There are many products to fracture fill emeralds, 99% of all emeralds are treated after all. In light of this, some labs and gemstone dealers felt the need to establish a standard to identify and classify the enhancing agents used in different countries.
In 1999, experts gathered in Switzerland and created a protocol. It is a three-tiered system for describing fracture filled emeralds in the trade. It is not universally accepted or implemented, but does provide a standard of grading where it is lacking. The Bern Agreement identifies three levels of disclosure:
It is one thing to identify an emerald as being treated, but identifying the specific treatment is a seperate story. Without distinguishing characteristics of the resin or oil present like the specific colored flashes above, it can be impossible to be certain of what the treatment is.
While many emerald dealers feel it is redundant to disclose the most common treatments in emeralds, the U.S. Federal Trade Commission is strict about disclosure of any type of gem treatments. There was already a huge scandal in the 1990s over oiled emeralds being touted as untreated by sales representatives when they were in fact treated. The heart of this problem was that the sales staff was not educated on what they were selling, and in turn gave false information to the customers as a result. This caused a crash in emerald prices as well as consumer confidence, with no one wanting to buy emeralds for years afterwards. Education is necessary, even if it is redundant to the sellers.
Also, don’t be afraid to ask questions. Dealers are legally obligated to answer all questions regarding what treatments have been performed on their emeralds, and any other gems they may by selling. However, do not expect them to know the full details of these treatments. The people who perform these treatments may not want to disclose all details as a trade secret.
The more intensive the treatment that has been performed on the emerald, the lower the price of the gem. So long as the customer knows what they are buying, there are no problems with selling any type of emerald.
E1332 | medium | play | left | “Emerald ID: E1332 – Weight: 1.60 Carats – Origin: Colombia”
Since clear emeralds are so rare, they will come with lab reports if the dealer is not collecting one for the emerald right away. These reports come from independent laboratories that customers can verify. In some cases the customer might request additional lab reports to verify previous ones. This does not mean one gem lab is better than another, it is simply a matter of getting a second professional opinion. Considering the premium on untreated emeralds, it’s understandable.