It takes intense pressure and temperatures north of 2,000 degrees for a diamond to form deep within the Earth. But these days, there’s another way to create a diamond: in a lab, where a diamond can go from seed to jewelry in a matter of weeks.
While lab-grown diamonds have been around since the 1950s, they have increased in popularity in the past five years and now make up an estimated nearly 20 percent of the global diamond jewelry market by value sold, according to diamond industry analyst Paul Zimnisky.
They’re typically much cheaper than natural stones, according to data from jewelry analytics company Tenoris, and consumers are attracted to those lower price tags. They also offer an alternative to mined diamonds, which have come under ethical scrutiny.
The surge of consumer interest has created “a lot more competition” in the lab-grown-diamond field, said Anna-Mieke Anderson, founder of lab-grown-diamond company MiaDonna. The gems so closely mimic natural stones that the Federal Trade Commission changed its jewelry guide in 2018 to strike the word “natural” from its diamond definition. It takes special equipment to spot the difference.
Can you spot the difference?
Choose which of these two photos shows a lab-grown diamond.
S0 how exactly are lab-grown diamonds made? The Washington Post visited Austin-based Clarity Diamond, one of the few companies to make lab diamonds in the United States.
A diamond is born
Lab-grown diamonds are not entirely man-made. In the early days, they often started with small slivers — or “seeds” — made from natural diamonds, said Clarity CEO Bob Basnett. Nowadays, Clarity uses seeds made from other lab-grown diamonds.
These seeds are inspected for quality, trimmed to a precise size with a laser and cleaned — first in an oven, then in an ultrasonic bath.
Once the seeds are squeaky clean, up to 50 of them are mounted on a holder.
Next, the seeds are put into a reactor to begin the growing process.
Diamonds are collections of carbon atoms that have typically been exposed to high pressure and high temperatures, causing them to bond and form a crystalline structure. In nature, the Earth does this under its surface. In the lab, the reactor helps get carbon atoms to collect on the seeds. The method Clarity employs uses much lower pressure.
Clarity uses a “chemical vapor deposition” (CVD) process to do this, one of two main ways lab diamonds are grown. In the CVD method, a vacuum system pumps all the air out of the reactor’s chamber for a few minutes to create the ideal growing conditions.
Next, hydrogen and methane are added to the chamber and broken apart. This process releases carbon fragments, which fall on the seeds.
Plasma heats the seeds so the carbon fragments bond to their surfaces.
“The plasma ball is kind of like the sun, and it’s creating the atmospheric nutrients that are going to rain down on the seeds in the garden and make it grow,” said MiaDonna’s Anderson.
Over about 50 days, the crystal structures grow, and rough diamonds are formed.
When the rough diamonds emerge from the reactors, they look more like rocks than sparkling jewels, said Clarity President Bill Holber. “The rough is sort of like a raw stone with edges. It doesn’t look like a gem.”
After being weighed and catalogued, they are sent to a cutting and polishing facility at Clarity’s partner, HRA Group in Toronto.
A diamond from the rough
In Toronto, the rough diamonds are analyzed by hand and computer to determine the best way to cut them. Depending on their size and shape, each diamond could become one gem or multiple stones.
“We geometrically decide what’s the most appropriate shape to maximize weight and purity,” said Ophir Stolov, a senior executive at HRA until earlier this year.
Once the best design is determined, lasers cut off the polycrystal, an outer layer of hard carbon that forms during the growing process.
Then lasers saw pieces off the rough diamond. The process takes an hour or less.
The gem is then sent to a bruter, which smooths it out and shapes the “girdle,” or thickest part.
A second machine called a combobruter removes excess material to form the desired shape. The combobruter uses a ceramic wheel, which is turned to dust as it cuts and shapes the harder-than-rock diamond.
Now, the gem is starting to look like a diamond.
It now needs polishing to create the many facets that cause a gem to sparkle.
Creating facets is done with rotating metal wheels coated with diamond powder.
The process is often manual and can take an experienced worker about seven hours, Stolov said. (For some parts of the process, an automatic machine is sometimes used.)
Once the diamonds are cut, polished and perfected, HRA sends them to the Gemological Institute of America (GIA) to be graded for clarity, weight, cut and color. This assessment helps determine the selling price.
Put a ring on it
To the naked eye, the lab-grown diamond looks identical to a natural stone. GIA, an education and standards nonprofit founded in 1931, uses the same criteria to grade both kinds of stones, said chief laboratory and research officer Tom Moses.
But Moses says he can spot the difference using special equipment: Natural diamonds often have a different growth structure. They also may have trace amounts of nitrogen trapped inside.
Once the gems have an inspection certificate, they can be sold to retailers.
In Annapolis, jeweler Constance Polamalu buys Clarity diamonds in part, she said, because they’re made in the United States and customers like to know gems’ origins.
Polamalu’s business, Bloomstone Jewelers, uses only lab-grown diamonds to craft glittering rings, earrings and necklaces at an affordable price point.
“What I see is people just loving diamonds and loving classic jewelry,” she said. “With lab, they’re wanting something they can afford that they couldn’t in natural.”
As the market shifts to accommodate more lab-grown diamonds, Moses said, “I think there’s a future for both.”
Tell us what you think
For your next diamond purchase, would you consider a lab-grown diamond?
About this story
Videos by Allie Caren. Photography by Danielle Villasana, Chloë Ellingson and Marvin Joseph. Editing by Karly Domb Sadof. Video production by Nicki DeMarco. Photo editing by Haley Hamblin. Design and development by Lucy Naland and Audrey Valbuena. Design editing by Betty Chavarria. Copy editing by Emily Morman.