Emerald treatments • Opticon vs. Oiling • Catfights

Posted by Richard W. Hughes & Ray Zajicek
Emerald treatments • Opticon vs. Oiling • Catfights

Emerald fissure filling with resins such as Opticon and oils such as cedarwood oil have generated tremendous controversy. What's all the fuss about?

Catfights: Enhancement codes & trade wars

1997—It is ICA Congress time and that means once again it's time for the biannual cat-fight over enhancements. For this year's main event, we nominate emerald and ruby. This article will deal primarily with emerald.

Enhancements, Opticon and outrage

We have read the various articles [1, 2, 3, 4] on fracture filling in the ICA Gazette over the past few years with detached amusement. Things started back in April of 1994, with Henry Levy's generally thoughtful essay on epoxy (Opticon) fracture filling. June of 1994 had Roy Albers drawing that famous line in the sand – Opticon is baaadd, worse than a two-dollar bottle of wine – he won't buy emeralds that have been Opticon treated; if all are thus treated, he won't buy emeralds. Finishing the job in October of 1994 was a Hong Kong dealer, weighing in against the evils of Opticon in the best tradition of a hellfire-and-damnation preacher. With a bit of artistic license, we will paraphrase his comments: 'Opticon is evil, it rots the soul (and might even bring down the government).'

Allow us trot out the big S word (science) in defense of the apparently heretical notion that there is little difference between traditional emerald oiling and Opticon. Given an oil or resin of the same refractive index, transparency and color, there will be no difference – we repeat – no difference in appearance. While Opticon does have a higher RI, the difference is negligible (1.545 for Opticon, versus 1.515 for cedarwood oil, 1.53 for clove oil and 1.52–1.53 for Canada balsam). Don't believe it? Take a parcel of green glass with an RI of 1.58, quench-crack the lot and then treat half with Opticon and the other half with cedarwood oil. Now mix them together. We buy dinner at Denny's for anyone who can accurately separate the two halves based on naked-eye appearance alone.

Table 1 compares the properties of some well-known fillers. For comparison purposes, we've included ice and water, which have a similar RI difference to that between cedarwood oil and Opticon. As we write this, new fillers are appearing on the market; rumor has it that they will be more stable.

Table 1: Fracture fillers compared

Filler type Refractive index Can be injected with pressure/ vacuum? Evaporative stability Solvent Color* Color stability
Glass 1.4-2.0+ Yes Perfect HFl (be careful!) Any Excellent
Palma; Epoxy 828; incorrectly translated into English as Palm Oil 1.570–1.572 Yes Excellent Aqua regia; heat; ultrasonic Colorless, turns milky with time Okay
Opticon resin (epoxy + hardener) 1.55 Yes Excellent ATTACK (methylene chloride – be careful!) Pale amber; can be dyed Turns yellowish orange with time, especially when heated
Canada balsam resin 1.52–1.54 Yes Good Ether Pale amber; can be dyed Unknown
Clove oil 1.53 Yes Poor Alcohol, ether Colorless to pale yellow; can be dyed Poor; darkens upon exposure to light
Cedarwood oil 1.495–1.510 Yes Poor Alcohol, ether Pale yellow; can be dyed Turns yellow with age
Water 1.33 Yes Lousy
Colorless; can be dyed. Excellent
Ice 1.3095 (mean) Yes Excellent below 0° C Fine Scotch whisky Colorless; can be dyed Excellent, but may waver after a few glasses of fine Scotch whisky

*In thin sections all of the above fillers are essentially colorless, unless dyed.

As one can see, differences between Opticon and "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. Give us the Cadillac crack filler any day.


Are you one of those old-timers who likes his emerald in its birthday suit – unenhanced in any way? Then fight back, for the fine folks at Hughes Associates (fax: 612-474-5438), makers of Opticon, have given us just the weapon. It's a little something called attack – the perfect Opticon solvent. Dump your stones in this stuff and watch Opticon disappear faster than a stool pigeon at a Mob picnic.


Mehul Durlabhji asks that gemologists develop simple methods for identifying enhancements. We think most gemologists would agree to this – however with one caveat: miners, enhancers, cutters, dealers and jewelers – the whole food chain – must restrict enhancements to simple methods. Sad to say, but, today, bomb-science enhancement technology requires bomb-science detection methods. The days of the 10x loupe are not just numbered, they are long gone. And considering the above reality, perhaps it's time that the industry started taking a good look at how best to start shelling out some shekels for research. The ICA could take a baby step in that direction simply by reducing membership and congress fees for qualifying gemologists, placing them in a similar position as the press. After all, we want to encourage positive research and discourage voodoo gemology. This will require dialogue between dealers and gemologists. 

Treatment vs. Enhancement

AFTER much contemplation (RZ) and a look at the dictionary (RWH), we have come to the conclusion that enhancement is the best way of referring to the methods used for altering the appearance/stability of gems. In common English, treatment is a cure for sickness, while enhancement refers to 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.

We believe the right idea is to create a situation where there is a level playing field for all members of the trade, miners, cutters, enhancers, dealers, jewelers, gemologists, and, most importantly, retail buyers. In today's gem trade, enhancements are a fact of life, but, unfortunately, the declaration of such treatments is not. We do not see the point of impaling ourselves on our own swords in an attempt to slay the minority of dragons who would misrepresent enhanced goods as natural. Yes, we do need to police our industry against such vermin. No, we do not need to kill our industry in doing it.

The slippery slope of code creep

The lack of a consistent enhancement disclosure policy has led to much needless wheel-spinning and hand wringing. Like the proverbial decapitated chicken, trade groups are constantly in a whirl, squawking and honking each time a new enhancement appears that does not fit into the established nomenclature. This has led to bizarre, Rube Goldberg like schemes aimed at "simplifying" enhancement disclosure. Witness the proposed fracture-filling statutes, which give us three different codes for what is essentially the same enhancement (ordinary oil [O], cedarwood oil/Canada balsam [E], and Opticon/glass [T]). [5] Do we really want this? Do we really need every single gem tested by a lab? We think not, not, not, not, not….

Wouldn't it make sense to simply say that the stone is fissure-filled, and then, if one has the ability to detect the type of filling, describe it, rather than performing code gymnastics? Try these codes on for size:

• Enhanced: fissure/cavity filled (colorless oil/resin/glass)

• Enhanced: fissure/cavity filled (colored oil/resin/glass)

• Enhanced: irradiated

• Enhanced: heat

• Enhanced: heat (surface diffusion)

• Enhanced: dyed

• Enhanced: impregnated (plastic/resin)

• Enhanced: coated

• Unenhanced

Perhaps a bit long, but we think most invoices are big enough. And no need for complicated decryption algorithms.

Dealer suicide

While we do support the idea of identifying the filler in the case of filled stones, to make this a requirement is to commit suicide. Frankly, few labs and even fewer dealers have the ability to detect the types of fillings used today. This has led some gemologists into the unfortunate cover-your-culet position of labeling everything Opticon-filled, even when it's not. Those labs that can detect the various fillers should do it (and can charge a premium for their services). But for those labs which do not have the equipment or expertise to make the distinction, we have only one comment: "Please, please just say [I don't] know."

Like Messrs. Levy, Albers, Wu and Durlabhji, we believe all enhancements should be declared to the consumer. Let's follow the advice of one gemologist, who at the 1987 ICA Congress stated the simple governing principle of his lab – putting oneself in the shoes of the buyer. He attempts to give all the information that you would want if you were buying the stone. Would you want to know if it had been fracture filled, oil, Opticon, glass or otherwise? We would like that information – what's been done, what's the stability – unequivocally, honestly, in plain language, not some cryptic code.

Future games

A man's eyes should be torn out if he can only see the past. Russian Proverb

Gem enhancements will not become any less effective, nor will detection become easier. Dealers tug – gemologists pull. For this, we have none but ourselves to blame. The gem trade must stop living in the past. Jade traders were willing to fight for the right to wax, but now whimper and whine because the tug of B-jade profits has destroyed the market and the pull of testing costs too much. Such a clever cat, the trade tugged for a better mousetrap, but now complains because all the mice are dead and it has nothing to eat.

We used to believe in magic. We thought that everyone could get rich by making silk purses out of sows' ears. But we failed to see into the future. We rubbed the magic lamp, the enhancement genie appeared, but now he's turned on his master. Suddenly we've decided that we don't believe in magic after all.

These authors still believe in magic. We still remember the magic that holding a fine Burma ruby or Colombian emerald first brought. We hope that when our children reach our age, they still believe in magic. We hope that when they hold a fine gem, they see a silk purse, not a sow's ear.


1. Levy, H. (1994) Fracture filling of emeralds: down the oily slope. ICA Gazette, April, p. 3.
2. Albers, R. (1994) Call it what you want, epoxy resin is wrong. ICA Gazette, June, p. 9.
3. Wu, T. (1994) Why epoxy resin is not the same as oil. ICA Gazette, October, p. 4.
4. Durlabhji, M. (1994) Tell all, and let the customers decide. ICA Gazette, October, p. 5.
5. Just where does Valvoline fit in?

See also Dogfights: Dealers vs. Gemologists

R S end dingbat

Author's Afterword

Ray Zajicek and I (RWH) wrote this article for the ICA Gazette (June, 1997, pp. 7–9), to coincide with the ICA Congress in Brazil, 1997. This was based upon an earlier article I had written for JewelSiam (Hughes, R.W., 1995, Devil's Advocate: On and on and on. JewelSiam, Vol. 6, No. 2, April/May, pp. 81–83).

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