SourcingDec 19, 2018
Take a Peek at the Largest Diamond Found in North AmericaEditorsApr 10, 2020
5 Interesting Facts You Might Not Know About Diamonds
Editor-in-Chief Michelle Graff recaps a webinar in which she learned more about the stones’ formation, inclusions and the oldest diamonds on Earth.
This 552-carat diamond was recovered from the Diavik Mine in Canada’s Northwest Territories in 2018, and holds the title of largest diamond ever found in North America. Canada is home to the oldest diamonds on Earth.
Last week, I wrote a blog post containing a list of 10 jewelry-related movies to watch while you’re safe at home to give both myself and our readers a break from coronavirus-related news.
I had a great deal of fun doing it, and it served as a much-needed reminder of how much I like to just write, not necessarily about a controversy or a lawsuit, or with clicks in mind, but just for the sheer pleasure of finding an expressive way of sharing something I enjoy.
With that in mind, I’m having fun again this week, this time by sharing five facts about diamonds gleaned from a webinar.
On Thursday, geologist Evan Smith, a research scientist at the Gemological Institute of America, held the first in what is going to be a series of online “Knowledge Sessions” presented by GIA.
The webinars will feature presentations on gemology from scientists, field gemologists and educators, continuing next Thursday with Mike Breeding, GIA senior research scientist, talking about identification methods for lab-grown diamonds.
(GIA is currently building a web page for its Knowledge Sessions; we will share it as soon as it is available.)
Smith’s talk, “The Unique Story of Natural Diamond,” focused on what makes the hardest substance on Earth—and one of the world’s most popular gemstones—so interesting to geologists.
I’ve interviewed and written about Smith’s research here and there over the years; he was the lead author of an article on blue diamonds that landed on the cover of Nature, a scientific journal, in 2018, and his diamond research made the cover of Science in 2016.
He alluded to both these studies in his presentation and taught me a few new things about diamonds as well.
Please feel free to comment below if you’ve learned anything, or if you just feel like saying hello. You also can view the presentation in its entirety on YouTube.
1. Diamonds form deeper in the earth than other minerals.
Most minerals including corundum (ruby and sapphire) and beryl (emerald, aquamarine and morganite) form in the Earth’s crust, which is the layer upon which we all live.
But not diamond, which Smith said is “completely exotic … because it is formed much deeper in the Earth,” beneath the crust at depths of 150-200 kilometers (93-124 miles) in the base of old, thick continents.
Some go even deeper than that, forming at the boundary between the Earth’s mantle and its outer core. These are known as superdeep diamonds.
(For those needing a visual refresher on the layers of the Earth, I found this diagram to be helpful.)
I had a great deal of fun doing it, and it served as a much-needed reminder of how much I like to just write, not necessarily about a controversy or a lawsuit, or with clicks in mind, but just for the sheer pleasure of finding an expressive way of sharing something I enjoy.
With that in mind, I’m having fun again this week, this time by sharing five facts about diamonds gleaned from a webinar.
On Thursday, geologist Evan Smith, a research scientist at the Gemological Institute of America, held the first in what is going to be a series of online “Knowledge Sessions” presented by GIA.
The webinars will feature presentations on gemology from scientists, field gemologists and educators, continuing next Thursday with Mike Breeding, GIA senior research scientist, talking about identification methods for lab-grown diamonds.
(GIA is currently building a web page for its Knowledge Sessions; we will share it as soon as it is available.)
Smith’s talk, “The Unique Story of Natural Diamond,” focused on what makes the hardest substance on Earth—and one of the world’s most popular gemstones—so interesting to geologists.
I’ve interviewed and written about Smith’s research here and there over the years; he was the lead author of an article on blue diamonds that landed on the cover of Nature, a scientific journal, in 2018, and his diamond research made the cover of Science in 2016.
He alluded to both these studies in his presentation and taught me a few new things about diamonds as well.
Please feel free to comment below if you’ve learned anything, or if you just feel like saying hello. You also can view the presentation in its entirety on YouTube.
1. Diamonds form deeper in the earth than other minerals.
Most minerals including corundum (ruby and sapphire) and beryl (emerald, aquamarine and morganite) form in the Earth’s crust, which is the layer upon which we all live.
But not diamond, which Smith said is “completely exotic … because it is formed much deeper in the Earth,” beneath the crust at depths of 150-200 kilometers (93-124 miles) in the base of old, thick continents.
Some go even deeper than that, forming at the boundary between the Earth’s mantle and its outer core. These are known as superdeep diamonds.
(For those needing a visual refresher on the layers of the Earth, I found this diagram to be helpful.)
Smith said “very energetic” volcanic eruptions that come from below 200 kilometers bring diamonds to the surface. They are a sort of “accidental passenger” in these explosions.
With them, they carry valuable information in their mineral inclusions, which most commonly include kyanite, garnet and olivine.
Diamond inclusions can help researchers understand the distribution of elements in the Earth’s layers, for example, or when plate tectonics started.
“The diamond is surprisingly good at preserving these materials,” Smith said. “It’s very hard and durable, and good at keeping things from diffusing, or leaking, out of it, and diffusing, or leaking, into it.
“There’s a tremendous of information trapped in these diamonds.”
2. Superdeep diamonds were completely misunderstood until a few years ago.
For many years, diamonds that form at depths greater than 200 kilometers were believed to be small and never gem quality.
But in the past four years, Smith said, researchers have found that many large, high-quality diamonds—Type IIa diamonds (stones with top color and clarity) and Type IIb diamonds, which are gray or blue because of the presence of boron—are actually superdeep stones.
Evan Smith and a team of researchers studied offcuts from Type IIa diamonds, like this 404-carater, to gain a better understanding of the elements in Earth’s deep mantle. Their research landed them, and this diamond, on the cover of Science magazine in 2016.
One example of a superdeep diamond is the 404-carat rough diamond recovered from the Lulo Mine in Angola in 2016 (pictured above). Immediately found to be Type IIa and D color, it was the biggest diamond ever known to come from Angola.
The 813-carat Constellation diamond from the Karowe mine in Botswana also is a superdeep diamond, as is the famous Hope diamond and, of course, the largest diamond ever found, the 3,106-carat Cullinan.
Smith said superdeep diamonds are identifiable by the presence of high-pressure mineral inclusions like Ca-pv, calcium perovskite.
3. There are more diamond types than you might think.
Generally, when we talk about diamond types in the trade, we think of Type IIa or Type IIb, terms that speak to a diamond’s physical appearance, its color and clarity and, thereby, its value.
But to geologists like Smith, there are also eclogitic and peridotitic diamonds, two terms I had never heard prior to Thursday’s lecture.
Peridotite and eclogite are two types of rock found in the Earth’s mantle, and diamonds can form in both. These are not superdeep diamonds but the ones found closer, relatively speaking, to the surface of the Earth, also known as lithospheric diamonds.
Peridotite is an igneous rock and is the predominant rock type found in the mantle. If researchers find olivine inclusions in a diamond, then it tells them the host rock was peridotite.
A metamorphic rock, eclogite is much less common. The presence of kyanite inclusions in a diamond indicates it formed in eclogite rock.
In 2018, Smith and a group of researchers completed a two-year study on included blue diamonds, like this 3.81-carat stone, that shed lights on how and where blue diamonds form. It was featured on the cover of Nature. (Photo credit: Robison McMurtry © GIA)
4. The oldest diamonds in the world are found in Canada.
Smith’s presentation included a timeline (who doesn’t love a timeline?) that illustrated just how old diamonds are relative to the history of, well, everything.
The Earth dates back 4.5 billion years while the planet’s oldest rocks, found in Northern Quebec, are 4.3 billion years old.
The oldest diamonds follow at 3.5 billion years old and, like the Earth’s oldest rocks, come from Canada, a fact I already was aware of after hearing Karen Smit, another GIA research scientist, speak about the GIA’s Diamond Origin Program back in the fall.
Smit said the oldest diamonds studied by geologists so far have come from the Diavik mine, which Rio Tinto owns and operates in partnership with Dominion Diamond Corp.
Some of Earth’s “younger” diamonds can be found at the Argyle (1.6 billion years old) and Ellendale mines (1.4 billion years old) in Australia, and in Sierra Leone, where the Zimmi diamonds are a spry 650 million years old.
To put this in perspective: All these diamonds are older than the Atlantic Ocean, which opened up when supercontinent Pangaea began to break apart about 200 million years ago, and the dinosaurs, which died off 65 million years old.
5. Pliny the Elder had something to say about diamonds.
Smith opened up his talk with a quote from Pliny the Elder, a Roman philosopher and naturalist who lived about 2,000 years ago: “Diamond is the most valuable, not only of the precious stones, but of all things in this world.”
And he concluded it with a quote from himself that I liked: “Every diamond tells a story from a place we can’t go and from a time long since passed.”
I’ve now shared a Pliny the Elder quote; my week is complete.
Have a great weekend everyone, and stay safe.
To put this in perspective: All these diamonds are older than the Atlantic Ocean, which opened up when supercontinent Pangaea began to break apart about 200 million years ago, and the dinosaurs, which died off 65 million years old.
5. Pliny the Elder had something to say about diamonds.
Smith opened up his talk with a quote from Pliny the Elder, a Roman philosopher and naturalist who lived about 2,000 years ago: “Diamond is the most valuable, not only of the precious stones, but of all things in this world.”
And he concluded it with a quote from himself that I liked: “Every diamond tells a story from a place we can’t go and from a time long since passed.”
I’ve now shared a Pliny the Elder quote; my week is complete.
Have a great weekend everyone, and stay safe.
More on Editors
The Latest
MajorsJan 09, 2026
Kendra Scott Taps Activewear Exec as CEO Chris Blakeslee has experience at Athleta and Alo Yoga. Kendra Scott will remain on board as executive chair and chief visionary officer.
SurveysJan 09, 2026
U.S. Holiday Retail Sales Up 4%, Visa, Mastercard SayThe credit card companies’ surveys examined where consumers shopped, what they bought, and what they valued this holiday season.
AuctionsJan 09, 2026
Christie’s Names New Global Managing Director for LuxuryKimberly Miller has been promoted to the role.
Brought to you by
Impacting Tomorrow TodayHow Jewelers of America’s 20 Under 40 are leading to ensure a brighter future for the jewelry industry.
CollectionsJan 09, 2026
Piece of the Week: Lionheart’s ‘Serenity’ Opal CharmThe “Serenity” charm set with 13 opals is a modern amulet offering protection, guidance, and intention, the brand said.
Weekly QuizJan 08, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
CollectionsJan 08, 2026
Pandora’s New ‘Bridgerton’ Jewels Celebrate Bees, Bows, and Blooms“Bridgerton” actresses Hannah Dodd and Claudia Jessie star in the brand’s “Rules to Love By” campaign.
Events & AwardsJan 08, 2026
Ana Khouri To Receive 2026 Gem Award for High Jewelry ExcellenceFounded by jeweler and sculptor Ana Khouri, the brand is “expanding the boundaries of what high jewelry can be.”
Brought to you by
Roseco Releases New Full-Line CatalogRoseco’s 704-page catalog showcases new lab-grown diamonds, findings, tools & more—available in print or interactive digital editions.
TrendsJan 08, 2026
Stuller’s Color of the Year Is a Stark Contrast to Pantone’s WhiteThe jewelry manufacturer and supplier is going with a fiery shade it says symbolizes power and transformation.
CollectionsJan 08, 2026
Gracie Abrams To Front New Chanel Jewelry CampaignThe singer-songwriter will make her debut as the French luxury brand’s new ambassador in a campaign for its “Coco Crush” jewelry line.
MajorsJan 08, 2026
Diamond Council of America Names New Board DirectorsThe nonprofit’s new president and CEO, Annie Doresca, also began her role this month.
ColumnistsJan 07, 2026
Peter Smith: Physical Retail—The Beginning or the End?As the shopping mall model evolves and online retail grows, Smith shares his predictions for the future of physical stores.
Events & AwardsJan 07, 2026
Melee Adds 13 New Designers to NYC ShowThe trade show is slated for Jan. 31-Feb. 2 at The Lighthouse in New York City's Chelsea neighborhood.
TrendsJan 07, 2026
Amanda’s Style File: Go for GarnetJanuary’s birthstone comes in a rainbow of colors, from the traditional red to orange, purple, and green.
SourcingJan 07, 2026
Diamonds Do Good Releases 2025 Impact ReportThe annual report highlights how it supported communities in areas where natural diamonds are mined, crafted, and sold.
CrimeJan 06, 2026
2 Jewelers Arrested After TraxNYC Diamond District BrawlFootage of a fight breaking out in the NYC Diamond District was viewed millions of times on Instagram and Facebook.
MajorsJan 06, 2026
Rio Grande Says These Are the Top Personalization Tools for 2026The supplier has a curated list of must-have tools for jewelers doing in-house custom work this year.
MajorsJan 06, 2026
Zales Tests Out A New LookThe Signet Jewelers-owned store, which turned 100 last year, calls its new concept stores “The Edit.”
MajorsJan 06, 2026
LeachGarner Appoints New Director of SalesLinda Coutu is rejoining the precious metals provider as its director of sales.
SourcingJan 06, 2026
AGA Announces 2026 BoardThe governing board welcomed two new members, Claire Scragg and Susan Eisen.
TrendsJan 05, 2026
Amanda’s Style File: New Year’s EditionSparkle with festive diamond jewelry as we celebrate the beginning of 2026.
IndependentsJan 05, 2026
Jeweler Ben Nighthorse Campbell Dies at 92The master jeweler, Olympian, former senator, and Korean War veteran founded the brand Nighthorse Jewelry.
TrendsJan 05, 2026
Pinterest 2026 Trend Report: Brooches, Bold Gold, Cool BlueIn its annual report, Pinterest noted an increase in searches for brooches, heirloom jewelry, and ‘80s luxury.
MajorsJan 02, 2026
Marc Metrick Out as CEO of Saks Global Executive Chairman Richard Baker will take over the role as rumors swirl that a bankruptcy filing is imminent for the troubled retailer.
Events & AwardsJan 02, 2026
Jan Mohr, Couture’s ‘North Star,’ Dies at 71Mohr had just retired in June after more than two decades as Couture’s retailer liaison.
SourcingJan 02, 2026
IDCA Elects New President, Board of DirectorsShekhar Shah of Real Gems Inc. will serve as president of the Indian Diamond & Colorstone Association in 2026.
CollectionsJan 02, 2026
Lalaounis’ 2026 Good Luck Charm Speaks to ResilienceThis year’s good luck charm features the mythical horse Pegasus, and is our first Piece of the Week of the new year.
