The noblest variety of the mineral beryl, emeralds are valuable gemstones known for their intense grass-green color.
Humanity has been searching for this stone since the Middle Ages and it is still very coveted today. To give you an idea, the emerald was already explored by the Egyptians around two thousand years before Christ, near the Red Sea.
Brazil is currently the 3rd world producer and the gems come from the states of Minas Gerais, Goiás, Bahia and Tocantins.
The emerald and its treatments
Hundreds of years ago, gemstone cutters learned to bathe emeralds in natural oils to fill in cracks and improve their appearance. Today these natural oils are still used but with artificial material. No matter what filler was used on your emerald, it will reduce the visibility of flaws and give the stone a finishing touch.
Fillers can eventually leak out or change. It is advisable to have the emerald examined by a gemologist to assess the need for cleaning or retreatment. Emeralds should be cleaned by hand using a soft toothbrush or damp cloth so as not to damage the filling.
The International Colored Gemstone Association (ICA), which brings together the most important producers and exporters of colored stones, determines that the sales documents and certificates contain a complete description of the treatment that the gem received to enhance the transparency, color and/or removal and filling inclusions.
It is always recommended to inform the customer when buying any jewelry that contains emeralds or treatments, as it is difficult to find untreated emeralds on the market. Treatment with oil or resin with green pigmentation is considered a counterfeit.
oil treatment
Treating precious gemstones with oil to fill internal fractures is common practice. Many types of oils are used to fill emeralds, for example colorless cedar oil, which is supposedly acceptable. It has a refractive index similar to emerald. Since it is quite sticky, it is not easy for it to penetrate the emerald's microscopic fissures, requiring some heat and pressure to get the job done.
Oil hides flaws and improves colors. However, these hidden flaws can make the stone more fragile than it appears, and may even make it unsuitable for use in jewelry making. This process often takes place even before suppliers and resellers have acquired the gem. Assuming they're honest, they just don't know how much the gem has improved. Due to the oil, you really won't be able to talk about the quality of the gem, which is a loss for the buyer.
Sooner or later, the oil will wear out. In other words, the “improvement” is not permanent. When it disappears, your gem will look bad.
Keep in mind that emerald in particular takes a lot of wear and tear. If you need to fix a crack, chip, or make any undercuts, lubrication is going to be a problem. Newer cuts will generally not match the rest of the gem. Also, you'll need to re-treat the gem to make it look nice, which takes time and money. Consider alternative gemstones rather than buying all oil-treated gemstones.
Opticon
Opticon is a plastic polymeric resin injected into the emerald, often under a vacuum, to fill gaps and improve color and durability. When heated, it has a high penetration in the cracks, helping in the resistance and to diminish the reflection of fractures.
Although it is more stable than the oil treatment, it will yellow and disintegrate over time and if it comes into contact with some solvents. Even after treatment with Opticon, emeralds can often become oily.
And you, would you buy an imperfect piece of jewelry that has been “improved”? Or would you look for an alternative stone? Share your opinion.
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2 Answers
I'm getting into the business.. I liked the explanation.
This is the reason for preferring rough stones.
I don't like the polished ones.