Race for the 100-carat Lab Grown
June 22, 23
Lab growns are getting bigger. Much bigger.
Last February the record for a polished lab grown diamond was held by a 16.41-carat princess-cut gem from China.
Today the biggest polished lab grown is more than three times the size, a 50.25-carat Type IIa crystal.
It was produced by Ethereal Green, in India, using chemical vapor deposition (CVD) and was then cut and polished into an emerald-cut G color, VS2 clarity gem named Shiphra.
There's every likelihood that the record will be broken again. So, is there any limit to the size of a lab grown? And are they simply trophy diamonds, or do they benefit the industry?
John Pollard is senior director of education at IGI, the lab that has graded many of the world's largest lab gown diamonds.
"I think as soon as we saw 50 carats, many of us probably said OK, well, the next logical benchmark is 100," he said.
"This is a history maker, because it's the first one to pass the half century mark in carat weight. How soon will we see this one surpassed? Possibly this year.
"But it's going to be very dependent on physical size capabilities versus limitations. I would expect that we will still see the record setters coming from CVD growth rather than HPHT."
CVD (chemical vapor deposition) is largely replacing the older HTHP method, which mimics the natural process of diamond creation using high pressure and high temperature.
CVD is capable of producing larger stones, but with one important limitation.
Without getting too deep into the science, the way the atoms of carbon bond together in CVD yields breadth rather than depth. The diamonds spread outwards as they grow, rather than upwards.
Rounds, cushions, princesses and other common shapes are generally cut from rough stones which have a depth that is around 60 per cent of the girdle diameter.
The depth of CVD diamonds can be 20 per cent or less, which is why the record-breaking 50.25-carat stone, and many other large CVDs, end up as emerald-cuts.
"The size breakthroughs we're seeing are attributable to the CVD manufacturing process which started as a sort of distant second place, but is now overtaking HPHT," said Pollard.
There is, of course, a limited market for huge lab growns, but producing them is a learning process that provides valuable lessons for the mass production of popular sizes.
"There's a lot of time and attention given to just one stone," said Pollard. "And that's not what this business is about right now.
"The goal is producing quickly, and selling in more conventional sizes. It's possible that there is no limit to how large we can eventually go."
Advances in lab grown technology aren't limited to increasing size or improving quality.
Producers have responded to the depth limitations of CVD by growing stones that can be cut as a leaf, cross, or other, flatter shapes.
Treatments that can change or intensify colors are also opening up a new world of opportunities.
IGI graded a 10-carat yellow diamond that was subsequently transformed into a pink gem, that was then re-submitted.
The color of lab growns can be so intense that they're literally off the grading chart.
Pollard said his labs have never graded a mined red diamond as anything beyond fancy, because they're so rare in nature, but they're now seeing lab grown reds that could qualify as intense or vivid. They may need to add new grades as a result.
Lab grown producers are proud of their achievements, he said, but also wary of revealing too much about their methods.
"This is a technology and IP may be involved, so they're not really keen on letting others peek behind the scenes too much," he said, and they don't like to say too much about a work in progress, in case something goes wrong.
Overall though, he acknowledges that lab growns are putting affordable diamonds back on the agenda.
"What I'm really most positive about is the fact that we have brought younger generations back towards diamonds and back towards jewelry.
"And I do have in my family Generation Z members, and millennials. And I am definitely seeing a resurgence of interest because of the affordability of lab growns.
"So it's compelling, because I think that we had a couple generations that were not totally interested, but now we have captured their attention."
Have a fabulous weekend.