Blog

Clarity Enhancing Substances

Natural Fillers

Cedarwood oil, Canada balsam, mineral oil, paraffin oil, beeswax, paraffin wax, cinnamon oil, clove oil, palm oil, castor oil, coconut oil, and 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, and evaporating away the excess water content to make natural maple syrup.

Producing concentrated oil from cedarwood is a highly industrialized process. It involves harvesting the trees, chopping them into fine particles, forcing high-temperature and 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.

There are three types of cedarwood oil:

  • Low-viscosity: commonly used for wood treatment.
  • Medium-viscosity: commonly used for aromatherapy, massage, and perfumes.
  • High-viscosity (scientific grade): commonly used in research as an immersion oil for high resolution (1000X) light microscopy work and for emerald enhancements.

How an Epoxy Resin Became “Palm Oil”

In the early 1980s, the Shell Chemical Co. developed a multitude of new, liquid-epoxy resins for a wide variety of industrial applications. For the vast majority of applications, epoxy resins are cross-linked by adding various reactive agents, an optional procedure commonly referred to as hardening or curing.

One of these new resins, No. 828, happened to have a refractive index (RI) of 1.573. Colombian emeralds have a RI of 1.57-1.58, while emeralds in general range from 1.565-1.59. (The favorite “traditional” clarity enhancer, cedarwood oil, has a RI of 1.51-1.52).

Colombian emerald enhancers discovered these new artificial resins. They became convinced the perceived clarity of their emeralds, after enhancement with Epoxy No. 828 (without the optional hardening procedure), was superior to those enhanced with cedarwood oil. Superior perceived clarity means a higher price per carat.

However, when consumers hear the term “epoxy,” they immediately associate it with glue. No one will buy an expensive emerald if they believe it’s held together with glue! So, the clever Colombian enhancers came up with a “solution” to the perception problem. They coined the trade name “Palma” for Epoxy No. 828. Promptly mistranslated as “palm oil,” the name misled many buyers into thinking it was a “natural” or “traditional” type of emerald enhancement.

A Voice of Reason

By the mid 1990s, several internationally prominent emerald dealers had published scathing essays and editorials on the evils of artificial resins. But the voice of one crying out in the wilderness — that is, SSEF Director Prof. Henry Hänni in Jewellery News Asia (June 1993) — poignantly suggested:

It is hypocritical to speak about the good old days when everyone used oil. For many years, the so-called oil used has often been a natural resin such as Canadian balsam or cedarwood oil. Natural resins were used because nothing better existed. (p.80)

Note: again, the word “natural” is a red herring. The entire process is artificial (RWH).

Hardened vs Unhardened Resins

Gematrat/ExCel

In 1995, Arthur Groom introduced Gematrat, an emerald clarity enhancement guaranteed for life that doesn’t change color or leak out of the stone. Capable of withstanding ultrasonic baths, steam cleaning, and the repolishing process without any changes to appearance, it’s also removable from its host stone, if necessary, without any adverse effect. In 1997, the lab added a UV fluorescent tracer to Gematrat to help gemologists identify the filler and determine how much was present in the stone. 

The name was eventually changed to ExCel after it was improved by the product’s maker, Clarity Enhancement Laboratory (C.E.L.) in New York. The C.E.L. website boasts:

Due to the great stability of the ExCel process, retail and manufacturing jewelers can sell their emeralds with the confidence that their beauty and luster will give their owners a lifetime of enjoyment.

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 to be a Colombian alternative to Gematrat/ExCel.

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

Conclusion

Protecting the consumer should be of paramount concern to everyone in the gem and jewelry trade. After all, it’s ultimately the consumer who puts food on our tables. 

In the Guides for the Jewelry, Precious Metals, and Pewter Industries (Section ruling 23.22), the United States Federal Trade Commission (FTC) states:

It is unfair or deceptive to fail to disclose that a gemstone has been treated if:

(a) the treatment is not permanent. The seller should disclose that the gemstone has been treated and that the treatment is or may not be permanent;

(b) the treatment creates special care requirements for the gemstone. The seller should disclose that the gemstone has been treated and has special care requirements to the purchaser;

(c) the treatment has a significant effect on the stone’s value. The seller should disclose that the gemstone has been treated.

Consumer Advice

  • AVOID hot and/or soapy water, ultrasonic cleaners, solvents such as acetone (nail polish remover), and alcohol.
  • Buy only from reputable jewelers.
  • Request an independent gemological laboratory report stating the clarity enhancement level of the emerald.

Trade Advice

  • AVOID cleaning emeralds with off-the-shelf acetone-based nail polish remover, as the vast majority contain a small amount of lanolin.
  • After soaking an emerald in acetone, oils and/or resins will dissolve. This will then necessitate discarding the acetone, flushing out the container, and refilling it with pure acetone. This process typically requires several cycles in order to thoroughly clean an emerald.
  • Occasionally, removing all fillers will require strong acids. Don’t attempt this without guidance from someone experienced in the procedure. Never attempt this without proper protective equipment, clothing, and ventilation.

Gemological Laboratory Disclosure Notes for Emerald Enhancements

AIGS (Asian Institute of Gemological Sciences)

AGL (American Gemological Laboratories)

  • None, Insignificant, Minor, Moderate, Significant.
  • Identified as Traditional (oils), Modern (resins), or both.
  • Website: http://aglgemlab.com

Bellerophon GemLab

  • None (Cannot be enhanced), No oil, Insignificant, Minor, Standard, Significant.
  • Addition of * denotes resin. (For example, “Minor*” means “minor resin”).
  • Website: https://www.gemlabanalysis.com

CDTEC (Center of Technological Development of the Colombian Emerald)

  • None, Insignificant, Minor (F1), Moderate (F2), Significant (F3).
  • Emerald without enhancement but residues which don’t improve the clarity: None.
  • Comments: Contains residues from the cutting process. Filler on request: Oil (If 100% cedarwood oil: Cedarwood Oil), Wax, Artificial Liquid Resin, Artificial Hardened Resin, or a mix of oil and resin.
  • Website: http://www.gemlabcdtec.com/home/en

DANAT (Bahrain Institute for Pearls and Gemstones)

GIA (Gemological Institute of America)

  • None (no fissures present), No indications of clarity enhancement (no or insignificant clarity enhancement), F1 (Minor), F2 (Moderate), F3 (Significant).
  • Filler not identified.
  • Website: https://www.gia.edu

GIT (The Gem and Jewelry Institute of Thailand)

GRS (Gem Research Swisslab)

  • None, Insignificant, Minor, Minor to Moderate, Moderate, Significant.
  • Only when the treatment is graded as “moderate” or “significant” will the presence of resin be explicitly mentioned.
  • Website: http://gemresearch.ch

GTL (Gem Testing Laboratory, Jaipur)

GTTL

Gübelin Gem Lab

Guild GemLab

ICA GemLab (International Colored Gemstone Association)

Lotus Gemology

NGTC (National Gemstone Testing Center)

SSEF (Swiss Foundation for the Research of Gemstones)

  • Emeralds with no fissures (very rare): as there are no fissures at the time of testing, these emeralds cannot and are not clarity enhanced by a fissure filler at the time of testing. In such a case, we will state on our report: no indications of clarity modification at the time of testing.
  • Emeralds containing fissures, but without any clarity modification by a fissure filler are described as follows: no indications of clarity modification in fissures at the time of testing. This is to express that this emerald contains fissures, which should be eye-visible even to an untrained observer. Any such emerald may be refilled at any time after we have issued the report We therefore strongly urge our clients to have such emeralds rechecked by SSEF before buying the gemstone, especially if the report is not a very recent one and if the emerald looks very clean without any visible fissures.
  • Emeralds which do contain fissures containing a filler substance for clarity modification are described as follows: indications of clarity modification. Minor (or moderate, significant) amount of oil (or artificial resin, etc) in fissures at the time of testing.
  • Website: https://www.ssef.ch

Stone Group Laboratories

  • No evidence of Clarity Enhancement, Minor Clarity Enhancement, Clarity Enhanced.
  • No mention of type unless requested by client.
  • Website: http://stonegrouplabs.com