CVD Synthetic Diamond Over 5 Carats Identified by GIA

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This 5.19 ct CVD synthetic diamond (10.04 × 9.44 × 6.18 mm, with J-equivalent color and VS2-equivalent clarity) is the largest GIA has identified to date. Photo by Johnny Leung and Tony Leung.

Originally published by GIA on October 5th 2016

Chemical vapor deposition (CVD) technology has accelerated over the last several years, and the rapidly improving techniques have produced large, high-quality near-colorless and colorless synthetic diamonds. Two samples over 3 carats were reported in early 2016 as the largest CVD synthetics. GIA recently tested a CVD-grown synthetic diamond that weighed over 5 carats, marking a significant milestone.

The 5.19 ct cushion modified brilliant measuring 10.04 × 9.44 × 6.18 mm was submitted to GIA’s Hong Kong laboratory for grading service. The stone was not disclosed as a synthetic diamond. Using the lab’s standard screening and testing processes, it was identified as CVD synthetic. Following examination, a GIA Identification Report was issued and the stone was inscribed on the girdle with the report number and the words “Laboratory Grown,” following GIA’s protocols for undisclosed synthetics.

This is the largest CVD synthetic diamond GIA has examined to date, and the largest reported in the jewelry industry. It had J-equivalent color grade and VS2-equivalent clarity, comparable to a high-quality natural counterpart. Natural-looking internal inclusions such as needles and clouds were the major features. Strong graining and a fracture in the table were also clearly observed under the microscope. The black inclusions that are often found in synthetic diamond, were not found in this CVD specimen. This stone could have easily been mistakenly identified as natural based on microscopic examination alone. This case highlights the importance of using advanced spectroscopic instruments as well as conventional gemological techniques to ensure an accurate identification. Link to Original Article

I will be writing more on the subject of lab grown diamonds in the coming days. If you are interested in the subject I would encourage you to join my mailing list! 

Largest Blue HPHT Synthetic Diamond in GIA Lab

A 5.03 ct Fancy Deep blue HPHT synthetic diamond was examined by GIA (left). Faint but sharp color zoning was observed (middle, field of view 4.77 mm) along with small metallic inclusions and a cavity at the girdle (right, field of view 2.19 mm). Photos by Sood (Oil) Judy Chia (left) and Kyaw Soe Moe (center and right)

The largest faceted colorless HPHT-grown synthetic diamond reported to date is a 10.02 ct E-color, VS1-clarity specimen, cut from a 32.26-carat piece of rough, was reported by IGI Hong Kong in 2015. The diamond was grown by NDT, or New Diamond Technology, is one of the founding members of the new International Grown Diamond Association. Recently, large colorless and near-colorless HPHT-grown diamonds by the Russian company have been investigated by GIA laboratories. The sizes ranged up to up to 5.11 ct. In January 2016, GIA’s New York laboratory examined a 5.03 ct fancy-color HPHT-grown type IIb synthetic diamond produced by NDT. this is the largest faceted blue laboratory-grown diamond studied so far. 

The notes from GIA's lab report stated that the 5.03-carat diamond exhibited a number of traits characteristic of diamonds grown using the high-pressure, high-temperature (HPHT) process, including color zoning and a cuboctahedral growth pattern. The stone was graded a VS1, fancy deep blue. 

"This emerald-cut synthetic diamond was color graded as Fancy Deep blue. This is a very attractive color with no other color component, a prized rarity among natural type IIb diamonds (the Blue Moon, for instance, was graded as Fancy Vivid blue). When viewed under a microscope, faint but sharp color zoning could be seen, indicative of the uneven impurity incorporation of HPHT synthetic diamonds. No strain was observed under crossed polarizers, indicating a very low dislocation density, which is also characteristic of HPHT-grown diamonds. It had VS1 clarity, with only very small metallic inclusions and a cavity observed at the girdle. Fluorescence and phosphorescence images collected using a DiamondView instrument revealed the sample’s cuboctahedral growth pattern, another feature of HPHT synthetics. The long-lasting chalky blue phosphorescence was further analyzed using spectroscopy, and the emission was found to originate from two broad bands centered at approximately 500 and 575 nm (figure 2, right). These bands have previously been reported in NDT’s type IIa and IIb HPHT synthetic diamonds (D’Haenens-Johansson et al., 2015). "

The evaluation of a lab-grown blue diamond of this size is considered by the researchers to be so significant that they opted to publish Lab Notes online ahead of the next quarterly edition of Gems & Gemology.  

To read Lab Notes GIA.edu

Harder than diamond

New Substance Is Harder Than Diamond, Scientists Say
By JONAH BROMWICHDEC. 3, 2015

A microscopic view of tiny diamonds made with the new technique. Credit Jagdish Narayan and Anagh Bhaumik

Researchers at North Carolina State University say they have developed a technique for creating a substance they are calling Q-carbon, which represents a third phase, or distinct form, of carbon alongside graphite and diamond.

The discovery could have many applications, notably in the fields of medicine and industry. But Jay Narayan, the lead scientist on the study, has made one claim about the technique that is certain to turn heads.

“In 15 minutes, we can make a carat of diamonds,” Mr. Narayan said. A carat is 200 milligrams.

The process of creating Q-carbon — which involves concentrating a very short pulse of laser light onto carbon — can produce minuscule synthetic diamond “seeds,” which can yield gems.

Diamonds that have been “grown” by depositing successive layers of carbon atoms on the surface of a thin slice of a natural diamond in an intense plasma field.Borrowing From Solar and Chip Tech to Make Diamonds Faster and CheaperNOV. 11, 2015
While the amount of diamond is tiny compared with the yield of traditional industrial techniques, the process can be carried out at room temperature and air pressure, the researchers say, meaning it could be easier to reproduce on a large scale than other methods, including one that has been drawing interest in Silicon Valley known as chemical vapor deposition.

The technique used to create Q-carbon, which was pioneered over the summer, was described on Monday in the Journal of Applied Physics. A tiny laser beam is trained onto a piece of amorphous carbon for 200 nanoseconds, heating it extremely fast. The spot then cools in a process known as quenching, creating Q-carbon.

It isn’t known whether the substance exists in the natural world, but Mr. Narayan suggested it could be present in the cores of planets.

Wuyi Wang, the director of research and development at the Gemological Institute of America and an expert on diamond geochemistry, said that while he would like to confirm the findings himself, “if they are true, it will be very exciting news for the diamond research community.”

He added that the journal is “quite credible” and he “pretty much trusts what they say.”

André Anders, the editor in chief of the journal, echoed Mr. Wang’s excitement, as well as his note of caution.

“This is one of those ‘wow’ papers,” he said. “I put a sticky note on the manuscript that said ‘pay attention to this one’ before the peer review even happened. But the second thought I have, and this is the scientist in me, is that I’m always skeptical.”

Mr. Narayan described possible uses for Q-carbon in creating synthetic body parts, improving tools like deep-water drills, and producing brighter, longer lasting screens for televisions and cellphones.

Casey Boutwell, who works on commercial licensing for scientific discoveries at the university’s office of technology transfer, said he was bracing for strong interest in the technique. “We don’t know exactly how this can be best applied, and we’re excited to get the market’s input,” he said.

Neil Krishnan, the director of technology platforms at the Swedish industrial toolmaker Sandvik Hyperion, called Mr. Narayan’s discovery “extremely interesting.”

“I still think it’s at a nascent stage for us to consider it a competitive threat per se,” he said. “But it would definitely be a new technology that we’d be interested in.”

A microscopic view of tiny diamonds made with the new technique. Credit Jagdish Narayan and Anagh Bhaumik
But Mr. Narayan and his colleagues say the potential for creating synthetic gemstones pales next to possible applications of Q-carbon, which the researchers said is magnetic, fluorescent and electroconductive.

Original Article