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The following article is reproduced without alteration from the lab notes of Gems and Gemology, the quarterly scholarly journal of GIA, as excerpted from GIA Insider. Volume 9, Issue 21.

Phenakite as a Rough Diamond Imitation

The GIA Laboratory regularly receives near-colorless transparent crystals, pieces of rough or fragments for identification, often because they were sold as – or are hoped to be – diamond. Such was the case with a 67.94 ct. near-colorless transparent crystal (figure 1) that was recently submitted to the New York Laboratory.

The specimen was similar enough to a water-worn dodecahedron-like diamond crystal to prompt submission to the Lab. It showed abundant dissolution features, parallel growth striations (figure 2), trigon-like features, and an orangy red included crystal. Initial physical indications, however, such as a lack of either adamantine luster or dispersion (both of which could have been obscured by the irregular surface) and a modest “heft,” suggested that it was not diamond. In addition, during spectroscopic testing the sample was placed on a block cooled by liquid nitrogen. When it was removed, the crystal did not feel cool to the touch as a diamond should have, indicating low thermal conductivity.

Further testing revealed that the specimen was doubly refractive and uniaxial, with a spot refractive index of approximately 1.65 and a hydrostatic specific gravity of 2.96. These properties ruled out glass, cubic zirconia and diamond. The crystal had a weak, pinkish-violet reaction to short-wave ultraviolet radiation, revealed no absorption lines in the spectroscope, and had no transmission luminescence. Step-like striations were evident, but the trigon-like features were raised, not depressed as trigons usually appear on a diamond.

 

Raman spectroscopy confirmed that the specimen was phenakite, Be2SiO4, which has a trigonal rhombohedral structure with one cleavage direction, and is often confused with quartz. Nevertheless, the rough exhibits features that could be mistaken for those of natural diamond. Interestingly, its etymology comes from the Greek word phenakos, meaning “to deceive.”

 

This entry was prepared by Donna Beaton, Joshua Sheby and Riccardo Befi of the GIA Laboratory in New York. For the latest findings from the GIA Laboratory, read the Lab Notes section in every issue of Gemology.

Fig. 1 (left) rough crystal thought to be diamond submitted to the lab , Fig 2 (right) showing parallel step-like growth striations similar to those seen on diamond.

 

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Oh boy… Where to begin… The recent GIA newsletter was not encouraging. Perhaps we should start by taking a look at how overzealous De Beers DTC sightholders tried to impress daddy earlier this year by buying up rough at insane prices to make themselves look better. Or perhaps we should look at how Argyle is in serious trouble after commencing an enormously expensive operation to convert the mine from open-pit mining to an underground operation. Even better, we might want to start by taking a look at the US economy lately, especially in regards to lowered consumer confidence in combination with a collapsed sub-prime market. Finally, diamond mining profits have dropped this year, as the decline of the USD (miners are paid in USD) against other world currencies, in conjunction with higher energy costs, more taxes and foreign policy. And if all of that doesn’t work, blame Canada.

Regardless of how we start to look at this situation, one thing is for certain, India is very concerned right now; and rightfully so considering they are the world’s largest diamond manufacturing center. Estimates are that India has $1 Billion USD in inventory sitting around right now that they cannot move (with additional inventories stored in New York, Hong Kong, and Antwerp). The overall market for diamonds in India and other parts of Asia are very good right now, but when the world’s number one consumer of diamonds (that would be the US) has an anemic demand for finished stones, this threatens to cripple everyone below that wrung on the ladder. According to GIA, a Surat manufacturer said rough that yields a carat or smaller finished stone is priced 15-20% too high for the current market; and that a major correction would have to take place before firms became profitable again.

On that note, it now costs more to purchase and manufacture lower quality rough diamonds than US retailers are willing to pay for the finished gem… Think back to Econ 101, that’s not a good situation for the manufacturer. Poor India, it gets better for them though right? Hardly. The Argyle mine in Australia, the world’s largest diamond mine by volume produced, is under imminent economic threat; so much so it is speculated that it’s parent company Rio Tinto has put the property up for sale (Rio Tinto has not commented). Considering that cutting centers in Ahmadabad, employ hundreds of thousands of cutters solely to manage the output from Argyle, India is concerned that the mine’s closure would leave hundreds of thousands jobless (it’s not like they can go down the street and work for another cutting center). Diamond cutters are a dime a dozen in India.

The De Beers DTC sightholders did not do the market a favor either when bidding each other up in price for diamond rough in tenders earlier this year. Apparently, they were trying to show an increase in the production volume their firms handled for the next sightholding term… not thinking about how they were going to liquidate the material once they obtained it. Pure genius at work there.

Finally, the US housing market scene and general overall economic decline has had an effect on diamond demand. According to the Consumer Board in August, “The number of consumers claiming present-day conditions are ‘good’ decreased from 28.3% to 26.4% in July, while those saying conditions are ‘bad’ increased from 14.5% to 16.3%.” In addtion: “Those especting business conditions to worsen within the next six months rose to 10.6% from 8.2%”. Surely, the collapse of the sub-prime housing market had no impact on consumer confidence right? People generally try and make the mortgage payment before purchasing diamond jewelry. Oh wait, they don’t do either? How strange.

Aerial view of the Argyle diamond mine.

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Before I go into a long tirade about this, let’s first examine the last major Thailand scam…

The last time the gem world was rocked by dishonest Thai dealers using atrocious practices targeted corundum, specifically sapphires which were subjected to beryllium diffusion. Beryllium diffused sapphires were released like the Great Flood upon the market into the hands of unsuspecting dealers. The problem was so great that it threatened to cripple the market for sapphires. Beryllium treatment is a process that replaces the trivalent aluminum in the crystal lattice with divalent beryllium. The color change process is very complicated, and due to this, other trace elements often give away a signature that can be detected. Without going into extreme detail (which would take pages to discuss), a brief example of Be treatment could be when: [Mg2+ + Be2+] > [Ti4+ + Si4+] a trapped hole of color is formed by Be2+ and Mg2+ to produce yellow color. If though instead you reverse this process so that [Ti4+ + Si4+] > [Mg2+ + Be2+], more donating electron ions exist to deform the trapped color hole and yellow color is not produced. Blue color can be produced in sapphires using the transfer of Fe2+/Ti4+. This practice lasted for years, even though gemologists could detect the process, many dealers passed the stones along unknowingly representing them as legitimate heat treated only or worse yet, natural untreated gems. For the most part this problem has settled down, but still rampantly plagues online auction venues such as eBay.

Now, in regards to Thailand and topaz… The industry has been aware of inexpensive colorless or light tan topaz being treated with Cobalt-60 radiation or X-Ray radiation that turns the stones into a lovely deep reddish/orange to deep pinkish-brown color. The purpose of this would be of course, none other than to defraud a buyer by making the material appear to be very costly precious or imperial topaz. The problem is, that with only 1 day’s worth of exposure to natural sunlight, the process is completely destabilized, and the material’s color washes out to it’s original color (or lack thereof rather).

The difference in price between common colorless/tan topaz and true imperial topaz is a difference between as little as $1-5/ct for common material and upwards of $1,000/ct for stones 10cts+ in size of super rich color imperial topaz. This practice has had an immense impact on the trade and is the equivalent of taking a direct hit by a 20 megaton hydrogen bomb. It is a seriously destabilizing move against the industry by fraudulent individuals.

This case has become rather personal for me, in that someone I am close to has been affected by this scam. The individual purchased a 30 ct+ topaz from a dealer that operates off of eBay. The material was represented as untreated and was sold for about $1000 for the stone. This unfortunately should have been the individual’s first clue, when the material was priced around $30-35/ct, that this could not possibly be the famed material from Oro Preto, Brazil that commands prices of $500-1000/ct in sizable stones. But regardless, this person was misled – as the material was represented by the dealer as untreated. Upon seeing this material, I immediately knew that something was dead wrong. The saturation was too deep, there were a couple bands of internal color zoning that are atypical of zoning formations of precious topaz, and it flat out just didn’t look right. Upon suspecting the worst, I gave my opinion on the material, and suggested that we subject it to natural sunlight. I took pictures prior to subjecting the stone to natural light. Unfortunately, I didn’t have any AA batteries available for my digital camera, so I used a film camera (hope the shots came out ok). When I develop the pictures I will upload them here.

The process was timed to expose the material for 8 hrs to direct sunlight. What happened within the first hour of exposure alone was horrifying… the material lost half of it’s color saturation. Within subsequent hours, the material lost more and more color saturation. What started out as a very deep gorgeous reddish brown topaz was reduced to barely a light tan stone within 5 hours. eBay is still a huge source, if not the number one source of this treated material. I can’t stress enough how important it is to know your source and know what you are buying and what treatments are out there.

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Last week on Palmetto Gemology, I began to establish a working foundation from which to further build this series. I hope that I have made it easier to understand how appraisals can vary so much due to the room for human error or differences of opinions.

This week I would like to focus on explaining what a customer or gem owner should expect from the process. Perhaps John and Laura Ramsey (husband and wife, and both are world renowned in the field), have said it best. Their perspective is that the consumer expects that “an appraisal, is an appraisal”, due to our culture which is rich in assembly line products and leads to an assembly line mentality when it comes to valuations.

The reality of this is of course, that no two stones are the same, as nature did not roll them off an an assembly line. This leads to the next obvious problem. Any local jeweler (or anyone for that matter), can give an “appraisal”. Simply because someone is a jeweler is not merit enough to take their word as gospel, as their guidelines by which they assessed the stone are unknown (the Billy Bob Gem Lab routine). If the consumer or gem owner chooses a gemological laboratory such as GIA, EGL, or AGTA, they gain a peace of mind in knowing that there is a standard and rigorous process that is followed each and every time a stone is submitted to one of these facilities. In maintaining strict protocols both in grading and in ethical standards, a “cert” from one of these institutions is regarded as an accepted and true analysis (whereas no one cares about the Billy Bob Gem Lab). From a consumer end, this helps to alleviate anxieties over how their stone will be graded.

I hope this helps in creating an understanding from the customer/owner’s end of the process. In a couple days I will begin explaining the process from the appraiser’s end, and then later in the week we will finally be ready to start getting to the meat of… what IS an appraisal. It may seem like this is being dragged out, but in order to understand what it is, we have to first examine preconceived notions and perspectives.

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Wow, what a touchy subject… the valuation process of what a gem is actually worth right? Think again… The term appraisal means different things to different people, depending on their perspective to a particular matter at hand. There are three contestants in the game of appraising gemstones: the appraiser, the owner of the gem, and of course the gem itself. The gem itself is the only one of the three that does not change, and is not subject to varying opinions. The gem’s physical properties are all objective and factual in nature. Biases, differing opinions, and even more complex issues may affect an appraisal. Gem owners tend to focus on the “value” of a gemstone (yet another term that people use that they do not understand the meaning of). We will address the misunderstood issue of “value” later in this mini-series.

Let us first address the issue from the perspective of the gem in question. For this example I’ll use a round cut diamond… D, VVS2, 1.12 cts, 6.50mm x 6.44mm x 3.98mm, no florescence, thin faceted girdle… sure, we all know the deal, and we’ve already come to a preliminary mental judgement on the stone (yes you have). Stop… by allowing preliminary judgements on the stone, you have affected your scotoma in either a positive or negative manner. To arrive at any preliminary judgement at this juncture is counterproductive to what we’re trying to establish. The color, clarity, dimensions and other attributes do not change. It is what it is. In this particular case the grader felt that the diamond was of ultimate and perfect white color (a subjective grade depending on who grades it). For instance, if 100 graders had a stone in front of them (GIA D in color), would they all grade the stone identically (we would hope so), but this shows the room for human error right off the bat. Moving onto a more complex issue… Clarity… we have assumed the stone in question is a GIA VVS2 (the number of inclusions in the stone doesn’t change) … yet how many GIA graders (*ahem* don’t fail me for the sarcasm) , would vary on the grade of a single stone if it was passed around (again out of 100 graders). …What do they call the person who finishes last in medical school? He/she is still a doctor. Likewise, with the gemology field, they’re still a gemologist. I hope this provides food for thought and creates a foundation for what I hope to accomplish in this mini-series.

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From my personal perspective HPHT is a four letter word. The acronym HPHT stands for High Pressure – High Temperature, and refers to an artificial process that some diamonds are subjected to in order to “reinstate their natural beauty”. Certain companies such as General Electric, have found an efficient process of turning natural Type IIA diamonds (no nitrogen present in the crystal lattice), that happen to have undergone turbulence or irregular pressure on their journey through volcanic pipes on their way to the earth’s surface, into colorless, pink, or even blue diamonds. Type IIA diamonds are the most rare diamond type, accounting for less than 2% of all diamonds mined. Originally, prior to HPHT treatment, these stones were mostly an undesirable yellowish brown color. HPHT can also turn Type IA diamonds (the most common diamond type), into green, yellow-green, or yellow diamonds after the process is complete. In a quick synopsis, HPHT subjects gemological imperfect diamonds to an ideal high pressure and high temperature setting that they never received in nature. This is the basis for a “controversy” between businesses who perform the process, the FTC, consumers, and oh yeah… gemologists. Thankfully the FTC has declared that any diamond subjected to HPHT has to have the process disclosed to the consumer. Unfortunately, this serves as little more than another platform to confuse most consumers on, since most consumers are not gemologists. Consumers tend to buy off of aesthetic appeal and emotion based decisions. Even informed consumers may not know a diamond has been subjected to the HPHT process, because the process is difficult to detect without costly equipment and proper training. Many seasoned gemologists have been deceived by HPHT (or have been intentionally set up by the GIA for training purposes *smile*). The bottom line, both personally, and from a gemology perspective, is that any stone that has been subjected to any artificial process – regardless of whether that process mimicks nature or not – is that the process should be disclosed to the consumer. The GIA has dedicated its time, finances, and efforts to not only detecting HPHT diamonds and noting them as such, but also to increasing awareness to consumers – and gemologists worldwide. It’s still a treated stone stupid… period.

Courtesy of Argyle Diamonds

Argyle’s natural rough diamonds are sorted at its Perth office where they are prepared for international sale by Rio Tinto Diamonds as an agent for Argyle Diamonds in Antwerp Belgium.

 

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In the 76 year history of the Gemological Institute of America, it has never before certified the origin of any gemstone. The folks at GIA now offer origin reports on emeralds submitted to the process. The primary focus of the process, is to make the distinction in the market between emeralds originating from Colombia, and those of all other locations (i.e. – Brazil, Zambia). An extra fine quality Colombian emerald is valued exponentially higher than an emerald of equal quality from say… Zambia. The difference between $25,000+ per carat and $2,000 per carat can come down to solely origin.

Many at GIA agree that this is an unfair step, because it intentionally sets emeralds apart from other gemstones by focusing on their origins, and not the origins of other stones, simply out of concern for monetary value. It can only be safe to assume that corundum (varieties – sapphire and ruby) will be next on the list to certify origin for the same monetary value reasoning (Burmese ruby vs. Kanchanaburi ruby). GIA has confirmed it will be adding certifications of origin for other varieties throughout 2007. Scanning Google on the topic, I came up with a story on http://www.colored-stone.com which can be found here.

GIA Report of Emerald Origin

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In September of 2003, around the timeframe of the ratification of the Kimberly Process by the United Nations, Wired Magazine (article is found here) decided to properly cover a blossoming area of the gemological field: lab created diamonds. They are not similar to diamonds… they are diamonds, both chemically and physically. Historically, Russian scientists have had the technology to produce gem quality diamonds, but never reliably or on any sort of a large scale operation. In fact General Electric produced diamonds decades ago for industrial purposes mostly, but the stones were always small (around 1/2 – 1 carat). That has now changed. Today everyone is getting in on the action – from the United States Navy Research Lab, to start up companies Gemesis and Apollo Diamonds, and they are producing large diamonds predictably and efficiently. The biggest use for lab created diamonds at this juncture in time seems to be not in the gem realm, but rather in the semiconductor world.

It is interesting to note how the leaders of both companies received personal messages people assuredly sent by DeBeers, stating that progressing with lab diamond technology is a perfect way to get a bullet in the head. At this time the ink on the Kimberly Process ratification was barely dry, DeBeers had already been publicly shamed – yet they were continuing with their typical show of force in a war that they know they are losing ground.

A little over 3 years after this story, it appears that the demand for lab created diamonds in the jewelry realm is very minimal. I regard this as a good thing, as it is easy to reproduce many gems that occur in nature and that are valuable, with great ease and relatively low cost. To the credit of many of these lab created gems, they are beautiful – even capturing inclusions and imperfections that would occur in nature, in the lab stone; but nothing compares to the beauty of something that took millions and millions of years to form, instead of something that took 3 days to whip up in a clean room.

Faceted lab created yellow diamonds from Gemesis — Identical chemically and physically to stones of natural origin.

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One of my friends asked me back in December what I knew about a recently discovered red beryl (bixbite) deposit found in 2003 in Madagascar. He showed me a pinkish-purplish oval faceted stone that he claimed was the new bixbite material. Stop…right now… sorry for those who hate spoilers early on, but there is NO red beryl found in Madagascar…. NONE! I would like to take this moment to thank Chuck Henley for providing clear insight into this matter.

The material referred to incorrectly as bixbite is in fact a new mineral altogether! Discovered in 2003 in Madagascar is a cesium rich analog of beryl, the key word being analog.The chemical formula for the material discovered is Cs(Be2Li)Al2Si6O18. The material has been named pezzottaite, after Italian mineralogist Federico Pezzottaite. At first this material was thought to be bixbite or either a new variety of beryl, both of which are false. The determining factors for this are a) the fact that pezzottaite crystallizes in a trigonal system rather than a hexagonal system as all beryls do; and b) pezzottaite contains lithium. As we all know, the other beryls that contain lithium are… oh wait… there are none. The specific gravity of pezzottaite is much higher than that of various beryls: 3.10 vs. 2.63-2.80 (varies with species). The refractive index of pezzottaite is higher, 1.60-1.62 as compared to 1.56-1.60 for beryls (varies with species).

On the note of red beryl, let us first look at its chemical formula: Be3(Al,Mn)2Si6O18. Named after Utah mineral collector Maynard Bixby, it is agreed upon worldwide that this material is among the rarest of the rare when it comes to minerals, and the gem grade material is supercostly and almost always tends to be small when it comes to this material, as cut gems average around 0.15-0.20 cts.

Red Beryl on Rhyolitic Matrix

Red Beryl on Rhyolitic Matrix

 

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A work in progress…

It will take me some time to gather my thoughts on how best to assemble this site to the benefit of all its intended viewers. Whether you are a broker or collector, the goal of this site is to focus on our commonality, and in turn further advance our knowledge and appreciation for our passion. My initial plans are to broadly cover the basics of a different mineral every week, and its applications to the gemological realm. I am considering structuring this on a thread based setup, in which each mineral will have perpetual updates. This will serve as an informative foundation upon which to further build the rest of the site. Of course updates regarding current trends, speculative trends, and jewelry ideas and information will also be included in these building blocks. Any individual who would like to showcase anything in their personal collection is more than welcome to post pictures, information, and personal thoughts on any piece of rough or faceted material. I wish to take a moment to ask everyone who is interested in any aspect of the field to provide insight on what they would like to see accomplished by this site.

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