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Home » Learning Center » Gemology » Gemstone Treatments » Emerald Enhancements: A Consumer và Trade Guide


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Treatment or Enhancement?

Enhancing gemstones lớn improve their appearance is a time-honored tradition dating back over 3,000 years. Archeologists discovered heat-enhanced carnelian dated lớn about 1,300 BCE in Tutankhamun’s tomb. The writings of Pliny the Elder (1st century CE) discuss many gemstone enhancement techniques including foil backing, oiling, và dyeing. These techniques, applied to gemstones for over 2,000 years, are still popular today.

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But what should we điện thoại tư vấn these techniques?

Quoting industry experts Richard W. Hughes & Ray Zajicek from Catfights: Enhancement codes & trade wars (1997):

After much contemplation (RZ) và a look at the dictionary (RWH), we have come khổng lồ the conclusion that enhancement is the best way of referring lớn the methods used for altering the appearance/stability of gems. In common English, treatment is a cure for sickness, while enhancement refers to lớn improving quality. Seeing as how treatments are a fact of life in today’s gem market, we might as well put a positive spin on things. Thus the authors feel that the most appropriate term is enhancement.

What Substances are Used for Emerald Enhancements?

In The Oil Treatment of Emeralds in Bogota, Colombia (1983), emerald expert và author Ron Ringsrud wrote:

Records of actual oiling of gem crystals go back as far as ancient Greece…. The principle of oiling is simply that while air-filled fractures in gemstones are highly visible, a fracture filled with a transparent oil or some other suitable material will be much less apparent. While the oiling changes only the clarity characteristics of the gemstone, the màu sắc will naturally be intensified because of the fewer apparent flaws blocking the passage of light.

Note: the change in màu sắc can’t be “natural” if it results from an enhancement process! (RWH)

Historically, jewelers have used various colorless or near colorless oils, waxes, and resins lớn improve the appearance of turquoise, jade, and emerald. These include liquid paraffin, mineral oil, clove oil, Canadian balsam, và cedarwood oil. More recently, jewelers have adopted a variety of synthetic liquids, such as epoxy resins and polymers, for gemstone enhancement.

When the enhancing liquid is strongly colored, the finished sản phẩm is considered not only clarity enhanced but also dyed. Such is the case with green Joban oil, commonly applied to lớn low-quality emeralds in Jaipur, India.



Can Other Types of Enhancements Improve Emerald màu sắc or Clarity?

Heating doesn’t improve the color or clarity of emeralds.

Irradiation can alter the màu sắc of certain emeralds with an appropriate iron-chromium-vanadium ratio, but the vast majority of stones will see no improvement.

Laser drilling to open a surface-reaching channel lớn inclusions, then removing them with strong acids, is a well-known process for đá quí clarity enhancement. However, the heat sensitivity of emeralds makes this process impractical, although it’s possible using a cold (non-thermal) ablation excimer laser. So far, laser drilling, dissolving of inclusions, & then filling with a transparent liquid is a virtually unknown practice with emeralds.

Types of Clarity Enhancing Substances

Soft Fillers

Surface-Hardened Fillers

Norland Optical Adhesive 65, a longwave UV–setting adhesive, & Opticon Resin No. 224.

Hard Fillers

Natural Fillers

Cedarwood oil, Canada balsam, mineral oil, paraffin oil, beeswax, paraffin wax, cinnamon oil, clove oil, palm oil, castor oil, coconut oil, & oleoresins.

Notes on Cedarwood

Since cedarwood oil is extracted from trees, it’s considered “natural.” However, the process isn’t as simple as hammering a tap into a maple tree, collecting the sap, & evaporating away the excess water content to make natural maple syrup.

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Producing concentrated oil from cedarwood is a highly industrialized process. It involves harvesting the trees, chopping them into fine particles, forcing high-temperature và high-pressure steam/solvent through the wood particles, then fractionally distilling the extracted substance. So, cedarwood oil is natural in the same sense that diesel fuel, kerosene, or gasoline are natural.


PermaSafe

Developed by the Centro Gemologico para la Investigación de la Esmeralda (CGIE) in Bogota, Colombia, PermaSafe is a permanent, synthetic, epoxy resin for emerald enhancements. This enhancement was intended lớn be a Colombian alternative to lớn Gematrat/ExCel.

The tracer in ExCel was eventually eliminated, mainly due khổng lồ the fact that labs in Colombia also added fluorescent tracers to their products. This lead khổng lồ the confusion of ExCel with other fillers.

Liquid Oil vs Liquid Resin Stability

In Catfights: Enhancement codes & trade wars (originally published in the ICA Gazette, June, 1997), R.W. Hughes and Ray Zajicek observed:

As one can see, differences between Opticon & “traditional” oils are minor, except regarding evaporative stability. Opticon will not evaporate as readily as cedarwood oil. We cannot speak for others, but in our book, this is better. If we have to buy a fracture-filled emerald, let it be one in which the filling is stable.

At the 1st World Emerald Congress held in Bogota in 1998, Colombian delegates professed their willingness lớn use only cedarwood oil in the clarity enhancement of emeralds unless the customers requested another. Financial motivation trumped promises, và artificial epoxy resin-enhanced Colombian emeralds continued khổng lồ permeate the market.

In early 2019, a prominent thủ đô bangkok thái lan dealer with decades of experience as an international trader in Colombian emeralds spoke with me on the condition of anonymity. He reported buying back stones he sold over đôi mươi years ago, originally purchased in Bogota. These stones had received a clarity enhancement with 828 epoxy resin. The dealer mentioned that compared to emeralds enhanced with cedarwood oil, “Palma” resin-enhanced emeralds not only looked better but also demonstrated much greater long-term stability. (Personal communication).

Flying from Bogota khổng lồ New York, Geneva or thủ đô bangkok thái lan subjects freshly enhanced emeralds khổng lồ drastic temperature, humidity, and air pressure fluctuations. This accelerates the process of unhardened oils and/or resins leaking out of surface-reaching fractures. Due to lớn this instability, emerald dealers commonly re-enhance their newly acquired emeralds upon arrival. This practice has resulted in several commercially manufactured multi-stage units on the market incorporating heat, vacuum, and pressure in order khổng lồ refill oils or resins in an office setting.

GIA Testing Results

To conduct durability tests, GIA researchers enhanced 128 emeralds with a variety of fillers. In Durability Testing of Filled Emeralds (2007), M.L. Johnson reports:

None of the fillers used for this study were stable to all the tests, but the results imply that the best candidate with regard to the durability of the filled emerald’s appearance under conditions of normal wear and care appears to lớn be a surface-hardened liquid.

To this day, an illogical snobbery still permeates the upper kết thúc of the emerald trade. The more stable resins are looked down upon, as they’re considered artificial or synthetic. On the other hand, cedarwood oil, with its inferior stability, is preferred because it’s considered natural.

Reality Check

Resins enhance the vast majority of emeralds on the market. Quoting emerald expert & ICA InColor Magazine Editor-in-Chief Jean Claude Michelou:

Consumer confidence is moving towards guarantees that the emerald’s initial appearance will not change with time. There are very, very few Colombian emeralds of significant form size that can enter into “no oil” or “minor oil” categories. This is a very tiny part of the market & ever tinier part of the production. Appropriate resins used without any hardener seem khổng lồ be much more stable since they mostly remain within the fissures. Respected labs, including Gübelin, GIA, AIGS, GRS, GIT, NGTC, Lotus & others, have aligned in not mentioning the type of filler, making no distinction on lab reports for oil or resin. (Personal communication)

With decades of experience in mining, cutting, and kinh doanh Brazilian emeralds from the Belmont Emeralds mine in Brazil, company representative Rafael Colen commented:

Our primary concern is providing our customers with an emerald with superior long-term stability. It makes no sense to enhance a beautiful emerald with unstable cedarwood oil just because it is considered a natural product. Resins provide far greater long-term stability, which is of benefit lớn jewelers, và ultimately to consumers. (Personal communication)

What’s the Most Effective Emerald Enhancement Technique?

Since fissures reaching the surface of an emerald are filled with air, forcing a liquid oil or resin into these fissures with pressure alone will often trap air in the bottom of the fissure. After releasing the pressure, the trapped air bubble will gradually expand, pushing the liquid out of the fissure. Therefore, the most effective technique involves first removing the air from the fissures in a vacuum tank & then introducing the emeralds into the filler liquid while under vacuum. This ensures the liquid will penetrate lớn the deepest reaches of the fissures without trapping any air bubbles inside.

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