G&G In a Flash: Nature’s Diamond Sculptures
March 4, 2026
Rough diamonds can form surprisingly familiar shapes. These examples include a tiny mortar (1.95-carat), raindrop-like crystals (3.23 ct each), a flame-shaped diamond (2.70 ct) with baguette diamond “logs,” a gummy bear shaped diamond (9.18 ct), and cube-like diamonds that resemble dice.
When you think of diamonds, you probably picture perfectly cut, sparkling gems set in engagement rings or fine jewelry. But long before a diamond is polished and faceted, it exists in crystal form—often rough, irregular and surprisingly full of personality.
Many rough diamonds form as octahedrons (eight-sided crystals that look like pyramids connected at the base) or macles (flat, triangular shapes). But some go far beyond these familiar forms, emerging from the Earth looking like nature’s sculptures.
GIA researcher Evan Smith recently studied a collection of these striking diamond crystals, searching for clues on how they formed deep underground. These stones are more than curiosities—they’re nature’s time capsules, preserving evidence of Earth’s geologic processes over the past millions to billions of years.
How Diamonds Take Shape Deep Underground
Diamonds form far beneath the Earth’s surface, under extreme heat and pressure, when carbon crystallizes into one of the hardest materials on the planet. Many grow into quintessential octahedral shapes, but that’s only the beginning of their story.
Despite their legendary hardness, diamonds aren’t indestructible. As they grow and make their way toward the surface, powerful natural forces shape them. Underground movement can cause diamonds to crack or split cleanly along natural weak points in their crystal structure. Hot fluids and molten rock can also partially dissolve their surfaces—a process called resorption.
Sharper, angular stones may reflect crystal growth or breakage, while smooth, rounded diamonds are often signs of heavy resorption
The result is a remarkable range of shapes and textures, created by ongoing crystal growth, breakage and resorption over time.
Rough Diamonds That Look Like…Everything
Windows
On the left are transparent, plate-shaped rough diamonds ranging in weight from 0.99 to 9.67 carats. On the right, a 2.22-carat diamond is shown against the sunset.
Geologists often describe diamonds as “windows” into the Earth’s mantle. Occasionally, that idea becomes literal. Some diamonds emerge as thin, transparent, plate-like forms that resemble panes of glass.
These shapes form when a diamond breaks along cleavage planes, creating flat, window-like surfaces.
Baguettes
These elongated rough diamonds resemble baguette cuts and range in weight from 1.84 to 7.10 carats, with lengths between 16 and 24 millimeters.
Elongated, baguette-like rough diamonds often form when a crystal breaks along natural cleavage planes. Many are later softened by resorption, giving them a naturally smooth, glossy, sculpted look.
Other Fun Shapes
Rough diamonds can naturally resemble familiar animal forms. Shown here are a parrot-shaped rough diamond weighing 5.99 ct (A), a sitting cat–shaped diamond weighing 5.68 ct (B), and two small dog–shaped diamonds weighing 2.15 ct and 3.66 ct, respectively (C). Also pictured are a yellow bird–shaped diamond weighing 5.69 ct (D) and a rabbit-shaped diamond weighing 2.79 ct (E). A white rabbit is included for comparison and was created using Adobe Photoshop Generative AI.
Natural diamond crystals can take on a surprising variety of forms, from a mortar-like bowl shape to dice or animal shapes. These unexpected silhouettes reflect the conditions under which each crystal formed.
Superdeep Diamonds
Some diamonds with fascinating shapes are superdeep diamonds. While most diamonds form about 90 to 120 miles below Earth’s surface, superdeep diamonds originate far deeper—up to 500 miles down. These diamonds are much more likely to appear irregular, because their journey to the surface is so dramatic.
Carried upward by powerful volcanic eruptions, they may be broken, reshaped and chemically etched multiple times. Many contain tiny mineral inclusions that act like microscopic time capsules, helping scientists understand conditions deep within the planet.
The 812-carat Constellation Diamond is a classic CLIPPIR diamond, combining incredible size and clarity with an unusual shape. It was sold in 2016 for $63.1 million, the highest price paid for a rough diamond to date.
CLIPPIR Diamonds
Among superdeep diamonds is a rare subgroup known as CLIPPIR diamonds. These stones tend to be unusually large, chemically pure and irregularly shaped. They often show heavy surface wear from resorption and contain very little nitrogen, which typically places them in the colorless range.
Some famous historic diamonds, such as the Cullinan Diamond, fall into this category. They’re prized not just for their size, rarity and beauty, but for what they reveal about Earth’s deep interior.
Why Rough Diamonds Matter
Rough diamonds may not sparkle like finished gems, but they have a different kind of allure. For scientists and gemologists, rough diamonds provide invaluable insight into how our planet works. For others, they’re a reminder that every polished diamond starts as something raw, unpredictable and shaped entirely by nature.
So the next time you admire a sparkling diamond, imagine the journey it took to get there. Behind every brilliant stone is a rough beginning, and a story written by nature itself.
