EMERALD REPORTThe refining process and its impact on pricing - September 2016

OILING

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It is human nature to strive for excellence, and this aspiration extends far beyond self-image. We strive to refine virtually everything created by Mother Nature, all that is beautiful in its own natural form – including gemstones. The richer the colour and the purer the mineral the better, and this epithet is true of any gemstone.

EMERALD OILINGThe refining process and its impact on pricing

So, in pursuit of possessing nature’s treasures, the likes of which can reap great financial rewards, people began several thousand years ago to refine emeralds in a fairly simple way: oiling. And to this day oil treatment is still the most common method used to enhance the emeralds appearance.

Of all the clear gem quality crystals mined across the globe, across every continent, there are very few ‘gem quality’ emeralds. Indeed, the highest quality green beryl stones are bestowed with complex internal crystal structures, known as the “garden-like” inclusions.

International market deems Colombian stones to be the king of emeralds. "They are the most highlyhighly prized for their classic, fine bluish green hue and vivid saturation which is typical of the Muzo and Chivor mines.

Graeme Thompson, Director - Bonhams Asia

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'2.91 carat no oil emerald from the Chivor mine, rare and a truly fine example'.

In spite of the fact that a stone with attractive defects is occasionally valued no lower than its defect-free counterparts with their thick, smooth colour, we nevertheless try to correct the natural “mistakes” in the defective stone, making what seems to us to be unattractive a little less noticeable. This is achieved by filling emeralds along possible fault lines with cedar oil or natural resin, known as “Canadian balsam”.

“As far back as Ancient Egypt the process of fracture filling this wonderful gemstone has been documented in scrolls and other ancient texts. Typically the preferred method to clarity enhance an emerald is through the filling of natural fissures and fractures with natural cedar oil or Canada balsam, although other more permanent methods do exist.

The next - moderate degree of treatment includes stones with multiple surface reaching fissures, one or more of which will be located across the table of the emerald. And the last category is comprised of stones that have multiple oil-filled fractures, many of which are surface reaching.

“The levels or degrees of treatment are set out by the LMHC (Lapidary Manual Harmonisation Committee) and divided into categories: no oil/insignificant and then minor, moderate and significant treatment. The stones in the first category (minor) often require a tiny amount of oil to make them reach their full potential. It may be the case that as little as one surface reaching fissure has been filled.

Unlike the treatment applied to sapphires and rubies most forms of enhancing the aesthetic appearance of an emerald are reversible. So if oiling emeralds is only a temporary solution, why is it still the most common treatment?

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Emerald before and after being treated with oil

'Fabio in our Bogota office handles this aspect of the business and is seen here holding a small compressor and bottle of cedar oil'.

Because this viscous liquid has the unique property of being able to penetrate even the smallest cracks and imperfections and crucially, does so because of its (almost identical) refractive index The natural oil becomes like a sort of glue, displacing air from the cracks, dissolving debris and cementing the crystals split parts.

Illustration of insignificant to moderate surface fissures on emeralds.

the IEEX balance sheet and fully insured.

Source: worldfinance.com - Elisabeth Matsangou

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Emeralds with no indications of clarity enhancement that require no fracture filling to improve the look command huge premiums over their counterparts. If a stone is graded as displaying ‘minor’ indications of clarity enhancement, prices could range from $12,000 to $18,000 USD per carat. If it belongs to the ‘moderate’ category, the value vary from $8000 - $12,000 per carat. Finally, an emerald displaying ‘significant’ indications of treatment could be worth from $4,000 - $6,000 per carat.

Despite the fact that oiling emeralds makes them more visually appealing, their value suffers. “Using a 3-carat stone of optimum colour and clarity as an example, with all things except level of treatment being equal, we can explore the effect this has on an emerald’s value.

The green emerald jewellery in the windows of Van Cleef & Arpels, Chopard, Boucheron, Cartier and other top tier brands will almost certainly have little to no treatment. Over the years, gemmologists in the major jewellery houses have sought out stones for their collections and have never compromised when it came to the quality of the gem.

For premium pieces of jewellery, you will have to pay the price, so if you are looking for more affordable emeralds, contact midrange boutiques or less well-known brands. They often work with emeralds refined to a moderate degree.

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"Various sizes and qualities of treated stones'.

These prices are only a rough guide though, as there a multitude of other factors that affect pricing ” explains George,. If you manage to find a completely natural emerald, be prepared to pay a high price for it: these stones are so rare that Smith estimates they constitute a mere 0.5% of the market and command premiums of 3-400% over similar looking but slightly treated stones.

7 carat moderate with the. Oil removed so that the stone can be examined in its natural state, on the right hand side there are numerous fractures and fissures which will almost disappear once it's refilled with cedar oil, leaving an eye clean stone.

Source: worldfinance.com - Elisabeth Matsangou

To summarise, cedar oil is 100% natural and as such is the favoured and most traditional form of treating an emerald. A stone with a minimal amount of treatment should never normally require re oiling however in recent years many dealers have begun using artificial hardened resins (which are essentially ‘glue like’ synthetic substance) to fracture fill emeralds, in the hope of providing a more permanent treatment to stones that require a lot of it.

This is often undertaken before the cutting process to ensure that any rough stones (that would normally have too many fractures and therefore be too structurally weak) are able to survive the pressure of the cutting and polishing wheel. Because of this, IEEX employ an oil only policy, working only with fine quality goods. Any reputable dealer should disclose the exact type of treatment an emerald may have been subjected to, preferably in w

And finally, it is also worth talking about the certificates, because they are your guarantee of quality. The most respectable and reliable are the two Swiss laboratories, Gubelin and SSEF, which undertake the inspection, analysis and certification of the majority of fine quality Colombian emeralds in the marketplace (including many emeralds supplied by IEEX).

Master Cutter Ricardo examining a 14.50 carat in our Bogota office for a Singapore Collector.

However, they don’t indicate in the certificate what kind of refining process has been implemented, paying attention only to the degree of enhancement the emeralds have undergone. “They refuse to specify the exact type of treatment agent not because it is impossible to identify it, but due to the fact that these laboratories will only state in writing what they can say with 100% accuracy. Missing one fissure that has been treated with a different filling material could jeopardise the laboratories’ reputation. SSEF is the only Swiss lab the gives any indication of the treatment type, classifying it as either ‘traditional’ or ‘modern’,”

Source: Graeme Thompson, Director - Bonhams Asia

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