Editor’ note: We are pleased to re-introduce our readers to Richard Hughes and his column, The Devil’s Advocate. A noted gemologist and former director of the Asian Institute of Gemological Sciences (AIGS), he is the author of the classic book, Corundum (Ruby & Sapphire).
Now a resident of Boulder, Colorado, he is finishing up a revised edition of Ruby & Sapphire, slated for publishing later this year. In the coming months, JewelSiam will be printing excerpts from this eagerly anticipated work, arguably the most complete ever to appear on the subject.
Hence, it is with great pleasure (and more than a certain degree of trepidation) that we once again unleash The Devil’s Advocate upon an unwary public. Of course, the editor would remind readers that the views of Richard Hughes are his own and do not necessarily represent the views of JewelSiam.
On treatment, option and outrage
I have read the various articles1,2,3,4,5on fracture filling in the ICA Gazette and JewelSiam over the past few months with detached amusement. But the latest fusillade has finally sent me over the top.
Things started back in April of 1994, with Henry Levy’s generally thoughtful essay on epoxy (Opticon) fracture filling. June had Tiffany’s Roy Albers drawing that famous line in the sand –Opticon is bad, worse than oil—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 was Tommy Wu, weighing in against the evils of Opticon in the best tradition of a hellfire-and-damnation preacher, With a bit of artistic license, I will paraphrase Mr. Wu’s comments: “Opticon is bad, it rots the soul (and might even bring down the government).”
Allow me to trot out the big S word (science) in defense of the apparently heretical notion that there is little difference between traditional oils and Opticon. Given an oil or resin of the same refractive index, transparency and color, there will be no difference, I repeat, no difference in appearance. While Opticon does have a higher RI, the difference is negligible (1.545 for Opticon, versus 1.515 for cedar wood 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 a RI of 1.58, quench-crack the lot and then treat half with Opticon and the other half with cedar wood oil. Now mix them together. I will buy dinner for anyone who can accurately separate the two halves based on naked-eye appearance alone.
Table 1 compares the properties of some well-known filler. For comparison purposes, I’ve included ice and water, which have a similar RI difference to that between cedar wood oil and Opticon.
As one can see, differences between Opticon and “traditional” oils are minor, except regarding evaporative stability. Opticon will not evaporate as readily as cedar wood oil. I cannot speak for others, but in my book, this is better, if I have to buy a fracture filled emerald, let it be one in which the filling is stable. Give me the Cadillac crack filler any day.
Fillers compared
| Filler Type | Refractive Index | Can be injected with pressure? | Evaporative stability | Solvent | Colora | Color Stability |
| Glass | 1.4-2.0+ | Yes | Perfect | HFI (be careful!) | Any | Excellent |
| Opticon resin(epoxy and hardener) | 1.545 | Yes | Excellent | ATTACK (mothylene chloride: be careful!) | Pale amber;can be dyed | Unknown |
| Canada balsam resin | 1.52-1.54 | Yes | Good | Ether | Pale amber;can be dyed | Unknown |
| Clove oil | 1.58 | Yes | Poor | Alcohol,ether | Pale amber;can be dyed | Poor; darkens upon exposure to light |
| Cedarwood oil | 1.495-1.510 | Yes | Poor | Alcohol,ether | Pale amber;can be dyed | Excellent |
| Water | 1.33 | Yes | Lousy | - | Colorless; can be dyed | Excellent |
| Ice | 1.3095(mean) | Yes | Excellent below 0oC | Fine Scotch whisky | Colorless; can be dyed | Excellent, but may waver after a few glasses of fine Scotch whiskey |
a. In thin sections, all of the above filters are essentially colorless, unless dyed.
On the attack
Are you one of those old fuddy duddies who likes their emeralds in virginal purity? Then go on the attack, for the fine folks at Hughes Associates (no relation), makers of Opticon, have given us the weapon. It’s a little something called ATTACK—the perfect Opticon solvent. Jut dump your stones in this stuff and watch Opticon disappear. With this stuff you can rest easy and Tiffany can again begin buying emeralds.
On a simpler world
Mehul Durlabhji asks that gemologists develop simple methods for identifying treatments. I think most gemologists would agree to this—however, with one caveat—miners and dealers must restrict treatments to simple methods. Sad to say, but, today, bomb science treatment technology requires bomb-science detection methods. The days of the 10x loupe are not just numbered, they are long gone.
On code creep
The lack of a consistent treatment disclosure policy has led to much needless wheel-spinning and hand wringing. Like the proverbial decapitated chicken, CIBJO, ICA and others are constantly in a whirl, squawking and honking each time a new treatment appears that does not fit into the established nomenclature. This has led to code creep. Witness the new ICA fracture-filling codes, which gives us three different codes for what is essentially the same treatment (ordinary oil [O], cedar wood oil/Canada balsam [E], and Opticon/glass [T]6.
Wouldn’t it make sense too simply to simply say that the stone is fracture-filled, and then describe what the filling is (or probably is), rather than performing code gymnastics? Try these codes on for size:
v Treated: fracture / cavity filled (oil / resin / glass)
v Treated: heat
v Treated: dyed
v Treated: coated
v Treated: irradiated
v Treated: heat (surface diffusion)
v Treated: impregnated (plastic / resin)
v Untreated
Perhaps a bit long, but I think most invoices are big enough. And no need for complicated decryption algorithms.
On laboratories and ostrich gemology
While I’m on my high horse, let me get something else off my chest. That regarding the recent decision by Asian gem labs to limit disclosure of glass infilling to those cases where it can be detected under 10x magnification or less.7 Like the three monkeys who refuse to be tainted by evil, these gemologists have apparently decided that if infilling / fracture filling can’t be easily seen, it just doesn’t matter. Might I recommend a similar course in identifying synthetic gems. If such labs can’t identify synthetic origin under 10x, then declare it natural and go have a beer. After all, you’d hate to break a sweat.
Apparently these labs have confused how the treatment affects a stone’s quality with the ability to detect that effect. Bleached-impregnated jadeite (B-jade) can be some tough stuff to identify with a microscope, even at 200x, but the treatment often has a tremendous effect on appearance.
On honesty
Like Messrs. Levy, Albers, Wu and Durlabhji, I believe all treatments should be declared to the consumer. Let’s follow the advice of AGL’s Cap Beesley, who at the 1987 Congress stated the simple governing principle of his lab—putting oneself in the shoes of the buyer. He give all the information that you would want if you were buying that stone. Would you want to know if it had been fracture-filled, with oil, Opticon, glass or anything else? I, for one, would like that information—what’s been done, what’s the stability—unequivocally, honestly, in plain language, not some cryptic code.
On faith
I would also like to know just how a laboratory arrives at its decision on an identification, origin or grade. If I send a rock sample off to a geology lab for testing, I get back a detailed written report, not some single-sentence statement saying “granite—gray—32.5 grams.” In contrast, many gemological labs apparently believe that nay data beyond weight and color will simply confuse the great unwashed.
It’s not that I don’t trust the labs—it’s just that, like the government, I shouldn’t be placed in the position of having to trust them. A fundamental tenant of science is peer review. One’s decisions must be subject to examination and testing by others. But interpreting and understanding the decisions of many gemological labs requires black magic—and this particular wizard lost his wand some time ago. So if you call yourselves scientists, leave the mind-reading to the Ouija board set. For the benefit of the paranormally-impaired like me, please print the testing data on the lab report.
On the future
A man’s eyes should be torn out if he can only see the past.
Russian proverb
Gem treatments will not become any less effective, nor will detection become easier. 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 B-jade has destroyed the market and testing costs too much. Such a clever cat, the trade asked 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 genie appeared, but now he’s turned on his master. And suddenly we’ve decided that maybe we don’t believe in magic after all.
I still believe in magic. I still remember the magic that holding a fine Burmese ruby or sapphire first brought. Today my daughter is five years old. I hope that when she is my age, she still believes in magic. I hope that when she holds a fine gem, she sees a silk purse, not a sow’s ear.
Copyright, 1995. R.W. Hughes. All rights reserved.