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Archive for October, 2007

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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On Monday the managing director of the De Beers Group, Gareth Penny, appealed to diamond traders worldwide to support De Beers in its backing of African attempts to retain rough diamonds for polishing within the continent. Citing the creation of jobs and stability for African democracies, Penny said “We don’t embrace this out of some misguided enthusiasm or altruism, we embrace it because it makes good business sense and because it’s the right thing to do.” Penny went on to invoke the global view on conflict diamonds, stating people no longer buy them and that mining companies wont invest money to extract from conflict areas, but that the industry needed a stable group of companies for maximizing supply since “producing and selling diamonds in or from a country of chaos or worse, conflict, is simply not an option.” (Clearly global view has changed De Beers policy on this matter, since it was not very long ago that the cartel had no problem at all selling diamonds from war torn African nations.)

The truth of the matter is that the diamond cutting industry in African nations is almost non existent by comparison to Belgium, Israel and the United States. Antwerp became exceedingly wealthy from Belgium’s rule of the Congo and the CEO of Antwerp World Diamond Centre, Freddy Hanard, has stated it does not view the African industry as a threat. De Beers called upon Antwerp, Tel Aviv and New York to fund this pet project, and to train African polishers. Penny from De Beers has said the company is currently spending more than $100 Million per year in the search for new mines, including areas in the Democratic Republic of Congo and Angola.

Courtesy of Canadian Arctic Diamond

Diamond Polisher (Photo: Canadian Arctic Diamond)

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Sotherby’s auctioned off an emerald cut 6.04 carat fancy vivid blue diamond ring which commanded the highest price per carat paid at auction for any stone in history.  The auction was held in Hong Kong, and the diamond originated from South Africa, as is the case with almost all blue diamonds.  The stone boasts a clarity of internally flawless (IF), and it is showcased in a simple platinum ring with an emerald cut white diamond flanking each side of the center stone. The winning bid was made by Moussaieff Jewelers of London, a very esteemed and respected firm; known for such acquisitions as the Moussaieff Red, and many other extraordinarily costly stones. The stone was sold by a private Asian collector. The diamond sold for $7.98 million USD, or $1.32 million per carat. The prior record at auction was $926,000 per carat for the Hancock Red, a natural red diamond sold in 1987.

This represents a very important statement about the current market demand of natural fancy colored diamonds, and the rapidly increasing popularity they have gained in recent years among serious collectors.

A Reuters video of the stone can be found here. This is the best video I have found to show the stone’s true color. Note the dim lighting in the picture below, the stone is actually a true bright vivid blue.

6.04 ct, IF, fancy vivid blue diamond – sets new auction record.

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In Late August, news began circulating worldwide that what could prove to be the world’s largest diamond had been discovered in South Africa. The small scale mining company claimed to have found a stone that weighed around 7,000 carats (around the size of a coconut), and was of a green color. An early publication by the BBC of the account can be found here. After reading this article you will see why I chose not to sensationalize this “finding”, as it seemed fraudulent from the very beginning.

Immediately, skepticism from everyone in the industry became widespread. De Beers publicly stated that the north-west province of South Africa was not known for producing diamonds, but that if tests proved conclusively the item in question was a diamond, that it would be the discovery of the century. This was a statement made by De Beers, in a rather nice way, to let everyone know that De Beers was stating those making the claim were full of it.

The Mail & Guardian article about the truth of the “stone” in question can be found here. I honestly do not wish to take a whole lot of time to cover this issue in depth. I knew in the beginning this was a bogus find, and the audacity of those who perpetrated this fraud is appalling.

“The world’s largest diamond” as it appeared on BBC.co.uk, next to a cell phone.

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Burma (Myanmar)… When it comes to localities known for the production of truly fine gemstones, few rival this region. It is after all, well renowned for its breathtaking and exquisite rubies, sapphires and peridot, among many others. While Burma is a beautiful country, rich in culture and natural resources, it has never been rich in economic or political stability. It has been ruled by a military dictatorship since 1962. The United States over recent years has levied and renewed embargoes against Burma, banning any product or material (including gemstones) originating from there. It is however still legal to possess gems obtained from Burma prior to the embargo, and of course it can be easily circumvented if you buy the stones from them indirectly (buy from a Thai dealer… or something like that).

But let’s focus now on an aspect of the gem trade that has thousands of years of history… the jade trade. Burma is the key player in a material known as jadeite. Jade is not actually a single mineral form, but a name given to gem varieties of both nephrite and jadeite. Jadeite is the more highly prized because of its rich translucent emerald green color. Many people are simply not aware of how valuable truly fine jadeite actually is, as they may only be familiar with the carved nephrite variety common in Chinese carvings; or worse yet “B-jade” grade varieties which are dyed to achieve their color. The other reason most are unaware of fine jadeite is that they simply have never encountered it, and probably will not ever encounter it.

In Burma, jadeite is found in both rivers and in mountain regions, as well as in situ deposits. In all but in situ deposits, jadeite occurs as boulders covered with a “thick skin”. “River jade” has an advantage in that the boulders are weathered and often the outside of the boulders are worn, exposing glimpses into the center of the stone and the color it contains. Jadeite recovered from mountain areas lacks the weathering necessary to erode the thick skin of jadeite boulders, so most often, no glimpses into the material are possible without cutting into the stone. In Burma, the jadeite is gathered (quite a painstaking process), and is then brought to trading centers in major districts for auctioning and open sale. Mandalay represents the largest market for jadeite, among other things… “Burma’s largest jade market is in south Mandalay, a city that is said to operate on the three “lines” – white (heroin), red (ruby), and green (jade)” (Cummings and Wheeler, 1996). Most jadeite is sold and resold several times before it is ever touched by a saw, and most of the material being sold is unknown in quality. Once cut open a boulder could contain a fortune in quality jadeite, or it could be worthless. Many dealers play this high risk game of spinning the jade wheel. Fortunes have been made and lost in a single small boulder.

Fine jadeite has a consistent deep emerald green color. Most fine material is highly translucent with some approaching transparency. In November 1999 a bangle bracelet made of Burmese jadeite (50mm inner diameter) sold for over $2.5 Million. The highest price ever paid for jadeite was for a strand of twenty seven (27) 15mm beads. The strand known as the “Doubly Fortunate” commanded $9.3 Million in 1997.

References:
Cummings J., Wheeler T. (1996) Lonely Planet Travel Survival Kit: Myanmar (Burma), 6th. ed. Lonely Planet, Hawthorn, Australia, 393 pp.

Gems & Gemology, Vol. 36, No. 1, pp. 2–26.

Lot of rough Burmese jadeite, note the reserve auction price in Euros.

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