While undoubtedly one of the most beautiful of all the colored gemstones, emeralds are also one of the most “included” of all gems. Emerald inclusions are not considered ‘flaws’ as they might be in diamonds, but are understood as part of the colored gemstone’s natural appearance and appeal. These inclusions are often referred to as “jardin,” the French word for garden, because of their garden-like or mossy appearance.
Eye clean emeralds do exist, but they are so rare as to be especially valuable, sometimes fetching as much as $50,000 per carat. On the other hand, a “significantly” treated emerald, one filled with epoxy resin and dyed, can be had for under $10 per carat.
The Gemological Institute of America classifies emeralds as a Type Three colored gemstone, meaning they are almost always included. As a result, the trade estimates that more than 95 percent of all emeralds have been subjected to some kind of treatment to improve their clarity. While some treatments are widely accepted in the trade, others are more controversial, and the degree to which these treatments are used will greatly affect the value of the colored gemstone.
Oil Treatment for Emeralds
By far the most common treatment for emeralds is oiling with cedar oil, a naturally viscous and colorless fluid from cedar trees. The refractive index of cedar oil is similar to that of emeralds, and when used to fill small fissures in the colored stone, cedar oil allows light to pass through in such a way as to improve the emerald’s overall clarity.
The typical oiling process begins by removing air and gasses from the cracks and fissures using a high pressure vacuum process. Next, the cedar oil is heated and applied under pressure to fill the small imperfections. The emerald is then cooled and the cedar oil returns to its viscous state, effectively filling the small imperfections in the colored gemstone. Finally, the oil treated emerald is cleaned and polished.
This traditional oiling process is stable and widely accepted, but it is not permanent, and eventually an oiled emerald will need to be re-oiled. Other colored oils have been developed that enhance the color of emeralds, but these are NOT generally accepted within the industry, and emeralds treated in this way are not nearly as coveted as emeralds that are simply treated with colorless cedar oil.
Other Emerald Treatments
Because cedar oil treatments are not permanent, other attempts have been made to find more permanent fillers for some heavily included emeralds. Prepolymers, polymers, epoxies, and artificial resins are sometimes used, with varying degrees of success and ethical responsibility. There are many types of epoxies used, and though used much less frequently than cedar oil, they are generally considered a less desirable treatment. When done properly, epoxy treatment can greatly improve the appearance and transparency of an emerald, but it can also be used to deceive the buyer.
Verifying the degree to which an emerald has been treated is a difficult task and requires both time and sophisticated equipment. Some emeralds may have been subjected to multiple treatments and can contain more than one kind of filler. In an effort to assure emerald buyers of the integrity of the colored gemstones they are interested in, the Gemological Institute of America offers Gemological Identification Reports.
These reports assess the characteristics of the colored gemstone (weight, measurements, shape, etc.), but most importantly, they indicate any detectable treatments used on the emerald. Thought these reports are not a true “grading” report like the ones issued for diamonds, they do classify the amount of filling inside the colored gemstone according to a scale that ranges from “minor” (F1), to “moderate” (F2), to “significant” (F3).
An emerald graded F1, (minor), would exhibit filled fissures that would fit into the VVS2 to VS2 diamond clarity range—simply put, the amount of filler used in the emerald has not changed the clarity in a significant amount. An emerald graded F2, (moderate), would contain filled fissures that correspond to the SI1 to SI2 diamond clarity range, and an F3 (significant) emerald would have filled fissures that would correspond to below the I1 diamond clarity range.
Any emerald that carries a significantly high price tag should have a lab analysis done to confirm what, if any, treatments have been done. While having an emerald that is not very expensive analyzed by the GIA might not be worth the extra time and expense, any emerald that claims to be untreated, or is said to have “no oil or resin” or “minor oil or resin” treatments should be subjected to analysis in a laboratory.
Where to Sell Large Carat Emeralds
If you are looking to sell estate jewelry set with large carat (high quality) emeralds, contact Diamond Estate Jewelry Buyers today. We are widely recognized as the best place to sell emerald jewelry in the country. Our emerald buyers specialize in vintage & antique emerald rings, earrings, and necklaces, as well as emerald jewelry from Van Cleef & Arpels, Cartier, Tiffany & Co., Harry Winston, and other luxury brands.