The maturing synthetic diamond technology and the overall decreasing manufacturing costs have made the production of gem-quality lab-grown diamonds financially possible even for smaller stones. The general concern within the jewellery industry has been the mixed selling of undisclosed synthetics and natural diamonds especially for melees over the past few years, which urged the diamond identification technology to evolve into a new phase where melee testing has been emphasised. Laboratories and technology companies have been doing their best to eliminate fears from the trade and consumers, sustain the integrity of the diamond pipeline, and maintain consumers’ confidence.
M-Screen
Antwerp Scientific Research Centre for Diamonds (WTOCD) has developed an automatic melee screening device, M-Screen, in collaboration with HRD Antwerp and launched on 17 September 2015 in Hong Kong. The machine feeds and screens round brilliant diamonds from one to 20 points for potential lab-grown diamonds, potential HPHT colour-enhanced diamonds, and simulants. It runs at a minimum speed of two diamonds per second (7,200 diamonds per hour). Depending on the size of the stones and the batches, the speed can fetch as high as 18,000 diamonds per hour.
“M-Screen is the fastest automated screening device on the market, screening complete parcels of melee instead of only sampling them,” Yves Kerremans, director of WTOCD and head of the project demonstrated the main advantage of the machine. For the upgrading issue, Peter Macken, CEO of HRD Antwerp said: “The high standards set by M-Screen make it the optimal screening device for the years to come. R&D is a continuous process yielding optimisation on the current technology mainly in terms of broader specifications. Therefore, it’s foreseen in the design of this instrument that other features can be added, or existing features can be upgraded.”
According to Macken, in addition to the commercialisation of M-Screen, HRD Antwerp has begun a brand new melee screening service on 15 November 2015 in their Antwerp lab using this machine. Furthermore, after evaluation, they will decide if they can offer the same service in their other labs or representative offices in India, mainland China or Hong Kong.
Automated Melee Screening
De Beers’ Automated Melee Screening (AMS) device developed by its International Institute of Diamond Grading & Research (IIDGR), is designed to scan near-colourless or colourless melees between one point and 0.20 carat in size, screening up to 500 carats of melees at once automatically. With an hourly rate of around 360 stones, the device determines if the stones are natural or not with high accuracy rate.
“The melee market continues to trade in large volumes. However, the risk of undisclosed synthetics is unfortunately looming ever larger, which means all business involved in – manufacturers, dealers, wholesalers and retailers – must have some form of screening and verification instruments to safeguard their business, inventory, and reputation with clients,” Jamie Clark, commercial director of IIDGR told Hong Kong Jewellery.
He stated that AMS is fail-safe for colours within the D-J range and fast tracks current CVD synthetics seen in the trade. It will also be possible to adapt AMS over time through software or hardware improvements, and they plan to provide upgrades to enable automated testing of fancy cuts and larger stones soon. “The main focus of AMS is to provide the most accurate and definitive result in the most efficient way possible,” he added.
As an ongoing service to support the industry, meet challenges, and build trade confidence for the long term, IIDGR has begun a new melee testing service this year on 26 October in Surat, India and on 12 November in Antwerp, Belgium, said Clark. Apart from using AMS, this full testing service offers other instruments for handling any tricky stone.
Upgraded Gem-3000
Gem-3000 Jewel Identifying Instrument is a spectral analyser based on full spectrum, developed by BiaoQi Electronics Technology Co, Ltd from China, came out in 2010. Through testing the spectral reflectance curves of gemstones, the machine is able to test their authenticity precisely and rapidly.
Realising the concern of synthetic melee in the industry, in 2014, the company upgraded the original instrument which was only for the verification of large stones, and added a new function of testing batches of melee, with no need of further analysing for natural Type IA and IIA diamonds, CVD synthetics, and HPHT-treated diamonds.
According to King Song from the company, although Gem-3000 needs manual operation, for the same total weight of one-carat melees, it only takes five minutes to test for diamonds less than one point in size and three minutes for stones larger than one point in size. “Unlike that some similar instruments in the market only serve as a reference, our machine’s testing result has conclusive significance,” he emphasised.
Apart from verifying loose and mounted diamonds, Gem-3000 can detect coloured diamonds and fancy-shaped diamonds. Regarding the market response, Song revealed that, in the past, most of their customers were from labs, while since August 2015 when synthetic melees have flooded into the market, many diamond manufacturers, wholesalers, and retailers have been purchasing this machine for in-house testing to ensure the natural quality of their products.
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