Tentative de fraude pour la certification de diamant CVD (de synthèse)

Salut,

voici une petite mise en garde qui circule parmi les diamantaires anversois:




""Several hundred man-made diamonds were sent to the International Gemological Institute ‎‎(IGI) in Antwerp and Mumbai to be certified as natural diamonds, raising concerns that a large ‎volume of these undisclosed CVD synthetic stones may have entered the market already.‎
Roland Lorié, the chief executive officer (CEO) of IGI, told Rapaport News that the company received an initial ‎batch of 145 stones at its Antwerp lab and that following tests proving the stones to be ‎CVD synthetics, the full parcel of more than 600 stones were presented to the lab. ‎
‎“A diamond dealer cannot tell the difference between natural and CVD synthetic diamonds ‎and it requires sophisticated machinery at the labs to make the necessary findings,” Lorié said. ‎‎“This means that there could be a large amount of undisclosed synthetic diamonds on the ‎market.”‎
An unnamed polished dealer, who had bought the synthetic stones on the open market --at natural ‎diamond prices-- submitted the goods to IGI for certification about two weeks ago after he was ‎unable to sell them as a parcel on the dealer market. ‎
Lorié said that the polished dealer and his supplier both claimed to be under the impression ‎that the goods were natural diamonds. ‎
Around the same time, a smaller parcel of 10 stones was submitted to IGI’s Mumbai lab by two ‎separate parties. IGI found that all these sets of goods were CVD synthetic diamonds and likely ‎came from the same source. ‎
IGI issued a trade alert to other laboratories regarding its findings. (See the IGI trade alert here). ‎
‎“Additionally, IGI decided to share detailed scientific information with other gemological ‎laboratories around the world, as we now suspect that the volumes of colorless synthetic ‎diamonds being released on the global markets have increased noticeably, and may perhaps ‎already be prevalent throughout the diamond centers,” IGI stated. ‎
The company worked with the Belgian Federation of Diamond Bourses (BFDB), the Diamond ‎Trading Company (DTC) Research Centre and the Antwerp World Diamond Centre (AWDC) to ‎alert the trade about the issue. ‎
DTC reported to sightholders that it has identified three recent instances of undisclosed ‎submission of CVD synthetics to grading laboratories in Belgium, India and China, whereby ‎each case had very similar characteristics and may have had a common source. ‎
''The DiamondView and photoluminescence results indicate that the CVD synthetics have been ‎heat-‎treated post synthesis and we note that the combination of characteristics is ‎strikingly ‎similar to that reported by the GIA [Wang & Moses 2011] for 16 CVD synthetics ‎received from ‎Gemesis Corporation,” DTC told sightholders. (See DTC statement here).
Stephen Lux, the president of Gemesis, said, ''Gemesis has been completely forthcoming about exactly what it is selling to the public. There are several other companies that are practicing the CVD technology, with some scale as to have capability for the few hundred diamonds that most unfortunately have been sold inappropriately. The recent 2-carat lab-created submission to GIA India (also not from Gemesis) is evidence of others’ capabilities. Gemesis can assure the industry with 100 percent certainty it has not been involved in selling its diamonds as mined, and the undisclosed diamonds referenced in the DTC and IGI alerts are not Gemesis diamonds.''
Lux added that Gemesis is ''committed to maintaining supply-chain integrity and providing knowledge of origin of its products.'' Each of the company's lab-created polished diamond larger than one-quarter carat are laser inscribed with an identifying number as part of the certification process.
''Gemesis also hopes that this unfortunate event will encourage the industry as a whole to be more proactive in assuring the success of lab-created diamonds in the right way and we pledge our cooperation in making that happen,'' Lux concluded.
Avi Paz, the WFDB president, explained that the diamond bourses require their members to ‎identify synthetics and disclose any treatments used on diamonds. He stressed that the ‎bourses are guided by clear rules regarding the trading in misrepresented or undisclosed ‎products, whether inadvertently or not. Any violations of these rules are referred to the ‎relevant bourse for disciplinary action and can be grounds for suspension, expulsion, fine or ‎other appropriate measure. ‎
‎“Together with the diamond laboratories, which have the means and technological ‎instruments to detect man-made and treated diamonds, our affiliated bourses provide ‎assistance in identification techniques and a secure structure,” Paz said. “It is in the interest of ‎our global business that it remains transparent so that consumers can receive full disclosure ‎about the diamonds they purchase.”‎
DTC added that trading in these goods could cause irreparable damage to reputation and could ‎undermine the integrity of the diamond supply chain, damaging both trade and consumer ‎confidence in buying...""

Source Rashesh Choksi Diamantaire.


La fraude consiste à envoyer des diamants créés "manuellement" dans divers laboratoires, soit pour détecter leur capacité à découvrir la supercherie, soit, en passant à travers les mailles du filet, obtenir d'office un certificat d'authenticité pour ces pierres de synthèse... Décuplant ainsi leur prix de vente!!

En conclusion: Si vous êtes amené à acheter des diamants (au dessus du carat!), essayez de connaitre le vendeur ou l'histoire de la pierre...


Une bonne à tous,

Ced

Bonjopur Ced,

Cela ne m'étonne pas , ce fût le cas aussi pour toutes les pierres de couleurs de synthèse. ( Et ce le sera pour l'éternité tant qu'il y aura des hommes.....mal intentionnés...)

Il ne faut pas oublier non plus que dans un lot de pierres naturelles il est facile d'y glisser une petit pourcentage de pierres de synthèses taillées de manìère identique, surtout facile avec des pierres synthétiques obtenues en autoclaves...type Gilson ou Chatam.

Belle journée...et merci de ce reportage.

Michel Zim

Salut Michel,

Ça a dû changer, parce qu'il y a quelques années, les diamants synthétiques coûtaient plus chers à produire que le prix d'un naturel. Aussi, on pouvait le détecter par l'aimantation je crois. J'ai dû manquer un bout de la suite de l'histoire.

Mais, aujourd'hui, même les plus honnêtes de nos fournisseurs pourraient se faire jouer.

Bonsoir Guy,

Oui les diamants de synthèse ( carbone pur cristallisé dans le système cubique par l'homme, à ne surtout pas confondre avec les Oxyde de Zirconium ( CZ) ) contiennent souvent de très petites traces de fer...peut être pas au point de les aimenter, mais au moins permettre de détecter ce fer par des examens en laboratoire et par des observations attentives avec de forts grossissements au microscope.

J'ai tendance à faire une très grande confiance à mes diamantaires.....canadiens ou américains....et je pense qu'il en serait de même pour les diamantaires sérieux de tous les autres grands pays du monde.

De toute façon, ce que prétendent imiter les hommes de la nature laisse toujours des traces détectables par d'autres humains aussi passionnés que les premiers......Je ne suis donc pas inquièt....

Belle fin de journée.

Michel Zim