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.)
Editors' Picks
Sponsored by
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
CollectionsApr 13, 2026
Uniform Object’s New Jewelry Collection Centers on the ‘Carbon Form’The “Carbon Form” collection explores the contrast between high and low materials, using rubber cord alongside 18-karat gold and gemstones.
Events & AwardsApr 13, 2026
JA Accepting 2026 Impact Initiative ApplicationsThe program provides essential funding to organizations for projects that enhance the jewelry industry.
Events & AwardsApr 13, 2026
Couture Announces New Show in MiamiThe jewelry trade show is launching its first open-to-the-public event in Coconut Grove this November.
Brought to you by
Las Vegas Antique Jewelry & Watch Show: Showcasing the Most Collectible Merchandise from Across the GlobeGain access to the most exclusive and coveted antique pieces from trusted dealers during Las Vegas Jewelry Week.
CrimeApr 13, 2026
JSA Offers Reward in Oregon Jewelry Store Armed RobberyJSA is seeking information about the gunpoint robbery of a Kay Jewelers location in Oregon’s Washington Square Mall.
Weekly QuizApr 09, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
WatchesApr 10, 2026
These Watches Have Increased in Value the Most Since 2018, Says Chrono24The top-performing watch models may be surprising, with Rolex and several popular pandemic-era picks notably absent from the top 20.
CollectionsApr 10, 2026
Ophelia Eve’s Toggle Pendant Holds Your SecretsThe “Scroll” toggle pendant, our Piece of the Week, opens to reveal a hidden message, mantra, or love letter written on washi paper.
Brought to you by
Protect Your Customers and Your BusinessYou deserve to know what you are selling–to protect your customers as well as your business and your reputation.
ColumnistsApr 09, 2026
Jewelry Demand Isn’t Stronger, Prices Are Just Higher Jewelers who misinterpret the state of the jewelry market risk employing the wrong retail strategy, cautions columnist Sherry Smith.
MajorsApr 09, 2026
Tiffany & Co. Promotes Nathalie Verdeille to SVP, Chief Artistic OfficerIn her newly expanded role, she will continue to oversee the jewelry category, as well as watches, home, and accessories.
WatchesApr 09, 2026
Jacob & Co. Rolls Out Its Sequel to ‘The Godfather’ Musical Watch“The Godfather II” watch plays two melodies from the mob film’s score, “The Godfather’s Waltz” and “The Godfather Love Theme.”
Events & AwardsApr 09, 2026
JCK Announces Jesse Itzler as 2026 Keynote SpeakerOrganizers have also introduced the new JCK Talks Signature Series, as well as an offering of watch-focused workshops and lectures.
SourcingApr 09, 2026
AGA To Honor ‘Quiet Leadership’ With New AwardThe Alan Hodgkinson Medal recognizes gemologists who are consistently generous with their time and expertise.
WatchesApr 09, 2026
Oris Names New CEO, CFOThe Swiss watchmaker is changing up its executive leadership team as part of a restructuring.
CollectionsApr 08, 2026
Hearts On Fire Celebrates 30 Years By Asking a QuestionThe “What’s Your Signature?” campaign invites women to think about how they see themselves.
SourcingApr 08, 2026
Sale of 42-Carat Blue Diamond Gives Petra a Boost in Q3The big diamond’s sale added to the company’s revenue though the market remains “challenging” overall, particularly for smaller goods.
Events & AwardsApr 08, 2026
AGS Confluence Returns with AI, Sustainability SessionsRob Bates of The Jewelry Wire will also moderate a panel on the state of the jewelry industry during the virtual event.
Events & AwardsApr 08, 2026
TJS to Honor 2 Longtime Former Stuller EmployeesThe Jewelry Symposium will honor two industry veterans with lifetime achievement awards at its upcoming May event.
TrendsApr 08, 2026
Amanda’s Style File: April’s Brilliant Birthstone With their durability, brilliance, and beauty, diamonds are the perfect stone for everyday birthstone jewelry.
MajorsApr 07, 2026
QVC Group’s Latest Filing Calls Its Future Into QuestionThe retailer failed to file its annual report on time and said it may issue a going concern warning.
ColumnistsApr 07, 2026
Peter Smith: A Tip to the Post Office on Workplace CultureSmith recounts a recent trip to the post office that included an uncomfortable, embarrassing, and public exchange between two employees.
GradingApr 07, 2026
GIA CFO David Tearle to Retire in June John Cowley, who has more than 30 years of experience, is succeeding Tearle as the lab’s chief financial officer.
CollectionsApr 07, 2026
Nerd Out Over Gemology Geek’s First Jewelry CollectionFounder Erica Silverglide has designed 35 colorful pieces set with fluorescing gemstones for the brand's first finished jewelry offering.
CollectionsApr 07, 2026
Ukrainian Jewelers Highlighted In New Book“Ukrainian Jewelry | Contemporary Jewelry and Art Jewelry from Ukraine” features 33 contemporary Ukrainian designers and studios.
CollectionsApr 06, 2026
Fope’s New Jewelry Debuts Are Golden“The Golden Now” campaign celebrates the here and now with the brand’s signature styles and a selection of its new pieces.
MajorsApr 06, 2026
Kecia Caffie, Corinne Bentzen No Longer With Signet JewelersSignet confirmed that Caffie, president of Zales and Banter, and Bentzen, who headed Blue Nile, have left the company.
CollectionsApr 06, 2026
Historian Tanzy Ward Pens Book on Black Victorians’ JewelryThe antique jewelry dealer talks about the importance of including Black Americans in jewelry history and preserving their stories.
