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.
The Latest
AuctionsAug 29, 2025
Sotheby’s UAE Sale to Feature 32-Carat Fancy Vivid Orangy Pink DiamondThe highlight of a single-owner jewelry and watch collection, it’s estimated to fetch up to $7 million at auction this December.
FinancialsAug 29, 2025
Movado’s Q2 Sales Rebound Despite Tariff ImpactCEO Efraim Grinberg noted a resurgence in the fashion watch market.
CollectionsAug 29, 2025
Piece of the Week: Mark Davis’ ‘Bullseye’ Necklace The “Bullseye” necklace, with vintage bakelite and peridot, August’s birthstone, is the perfect transitional piece as summer turns to fall.
Brought to you by
Rallying Call for the Jewelry Industry on Tariffs and Other Key IssuesJewelers of America is leading the charge to protect the industry amidst rising economic threats.
Supplier BulletinAug 28, 2025
Clientbook Is Helping Jewelers Turn Clienteling Challenges into Wins with Hands-On Training and CoachingSponsored by Clientbook
Weekly QuizAug 29, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
GradingAug 28, 2025
GIA’s New ‘Quality Assessment’ for Lab-Grown Diamonds Is Coming It will classify lab-grown stones into one of two categories, “premium” or “standard,” in lieu of giving specific color and clarity grades.
SourcingAug 28, 2025
Botswana Declares Public Health Emergency Amid Diamond Sales SlumpPresident Duma Boko addressed the country’s medical supply chain crisis in a recent televised address.
Brought to you by
Taking the Moment Head On: How Rio Grande Champions the Present & Future of Fine JewelryAs a leading global jewelry supplier, Rio Grande is rapidly expanding and developing new solutions to meet the needs of jewelers worldwide.
MajorsAug 28, 2025
Borsheims Names New Jewelry BuyerFormer Free People buyer Afton Robertson-Kanne recently joined the retailer.
IndependentsAug 28, 2025
Sissy’s Log Cabin Donates School Supplies to Memphis StudentsThe jeweler teamed up with two local organizations for its inaugural “Back to School and Bling” event.
SourcingAug 27, 2025
11,685-Carat Emerald Recovered From Zambia’s Kagem MineDubbed the “Imboo,” or “buffalo,” emerald, the rough gemstone is part of Gemfields’ latest emerald auction, which is taking place now.
SurveysAug 27, 2025
Consumer Confidence Slips in August Amid Job, Income WorriesPlans for dining out, booking vacations, and buying big-ticket items were down.
CollectionsAug 27, 2025
Mined + Found’s New Collection Gets Playful The “Play” collection centers on nostalgic toys that have kinetic elements to carry playfulness and wonder into adulthood.
CollectionsAug 26, 2025
Does Your Jewelry Stack Need a Snack?Designer Christina Puchi, the creative force behind CCWW Designs, has created charms and pendants based on iconic candies and crackers.
WatchesAug 26, 2025
Nick Jonas Gets Nostalgic in New Fossil CampaignThe Jonas Brothers star showed off new timepieces against the backdrop of his favorite spots in his home state of New Jersey.
IndependentsAug 26, 2025
Hinkamp Jewelers Celebrates 70 YearsThe family-owned jeweler in Fayetteville, North Carolina, is in the hands of the second generation.
ColumnistsAug 26, 2025
Back to School, Back to Style: Why August is Prime Time for Self-GiftingIn his latest column, Emmanuel Raheb shares tips for encouraging customers to treat themselves to new jewelry.
WatchesAug 25, 2025
London Jewelers Brings Rolex to Historic Hamptons HomeThe new stand-alone Rolex boutique is housed in the former Odd Fellows Hall, a landmark built in 1897.
CollectionsAug 25, 2025
Tennis Star Madison Keys Has the Perfect Necklace for the US OpenThe Brilliant Earth ambassador co-designed a diamond medallion featuring meaningful symbols.
TrendsAug 25, 2025
Amanda’s Style File: That’s a WrapWrap jewelry is more than just a trend; it’s the perfect motif for the coming season of layering, scarves, and pumpkin spice.
WatchesAug 25, 2025
WatchTime NY Show Returns for 10th Anniversary EditionThe three-day watch collector show, coming this October, will feature 44 exhibiting brands, as well as a new dinner experience.
GradingAug 22, 2025
Former Head of GIA India Promoted to Oversee Global Operations Sriram “Ram” Natarajan is now GIA’s senior vice president of laboratory operations and is based out of the lab’s headquarters in Carlsbad.
CollectionsAug 22, 2025
Piece of the Week: Retrouvaí’s ‘Diamond Vein Bond’ CollarThe one-of-a-kind collar represents the beauty of imperfection and the strength to rebuild.
MajorsAug 22, 2025
Kendra Scott Returns as CEO of Her Jewelry EmpireThree C-suite executives, including former CEO Tom Nolan, have resigned as part of what the company describes as a “transition.”
MajorsAug 21, 2025
Claire’s Finds Buyer, Could Save up to 950 StoresThe retailer, which recently filed Chapter 11, inked a deal to sell its North American business and intellectual property.
MajorsAug 21, 2025
Target Names New CEO as Sales Continue to Lag Target CEO Brian Cornell will step down in February and be replaced by the company’s chief operating officer, Michael Fiddelke.
Policies & IssuesAug 21, 2025
JA, IDMA Talk Tariffs With Execs in DC The group met with the president's senior trade advisor earlier this week to express the industry’s concerns about the effects of tariffs.
