< Science of Diamonds / Diamond Discoveries
A Massive Blue Diamond Discovery Could Rewrite the Record Books
Recovered from South Africa’s legendary Cullinan Mine, the 41.82-carat natural blue diamond ranks among the rarest finds on Earth, and it will have a major impact on the local community.
New Petra blue diamond discovery, January 2026 (Petra Diamonds)
Petra Diamonds has just announced the discovery of an almost unbelievable 41.82-carat natural blue diamond from the legendary Cullinan Mine in South Africa. Early images and information from Petra suggest it is of exceptional color and clarity, placing this stone squarely among the most important blue diamond discoveries of all time.
Blue diamonds already occupy the rarest tier of natural gemstones. A blue diamond of this size, recovered from one of the world’s most storied mines, immediately invites comparison to some of the most valuable diamonds ever sold. Yet, for all the excitement surrounding the find, some of the most important chapters of this diamond’s story have not been written yet.
Below is what to know about this incredible new blue diamond discovery.
Meet the Expert
- Grant Mobley is the Jewelry & Watch Editor of Only Natural Diamonds.
- He is a GIA Diamonds Graduate.
- He has over 17 years of jewelry industry experience, starting with growing up in his family’s retail jewelry stores.
Why Type IIb Blue Diamonds Matter
This natural diamond belongs to the ultra-rare classification of Type IIb diamonds, which means that it contains trace amounts of boron and little to no nitrogen. In a natural diamond, boron changes everything. Boron alters the way light moves through the diamond, absorbing red, orange, and yellow wavelengths and producing the blue and grayish-blue tones collectors prize.
Type IIb diamonds account for only about 0.1 percent of all natural diamonds, according to the GIA. This makes them among the rarest materials found in nature. Most of the world’s most famous blue diamonds fall into this category, and their scarcity places them at the very top of the diamond market. Some Type IIb diamonds even conduct electricity, which is a scientific curiosity that makes them even more fascinating.
The Cullinan Mine’s Unmatched Legacy
Cullinan Mine holds a singular position in diamond history. Discovered in 1902, the mine produced the 3,106-carat Cullinan Diamond, the largest gem-quality diamond ever found, later cut into nine principal stones that now reside in the British Crown Jewels. Beyond its colorless treasures, Cullinan has also earned recognition as the world’s most important source of natural blue diamonds.
Two Cullinan discoveries define the modern benchmark for blue diamond value:
The Blue Moon of Josephine is a 12.03-carat Fancy Vivid Blue diamond. It sold in 2015 for $48.4 million, setting a record price-per-carat and total price for a gem at the time.
The De Beers Cullinan Blue is a 15.10-carat Fancy Vivid Blue, Internally Flawless diamond. It sold in 2022 for $57.5 million, becoming the most valuable blue diamond ever sold at auction.
Both of these famous diamonds came from Cullinan, and both achieved their staggering prices only after meticulous cutting revealed their optimal color, size, and clarity. The newly recovered 41.82-carat blue diamond has the potential to surpass even these legendary stones, but no one will know until expert cutters finish their work.
The Long Road from Rough to Polished
Fancy color diamonds present the greatest challenge in diamond cutting. Every decision involves a careful balance between preserving weight and maximizing color. One incorrect angle can diminish saturation, and one wrong cut can cost millions in value.
For a stone of this importance, analysis alone can take months. Experts will study the internal structure, color zoning, and crystal orientation of the rough before committing to a cutting strategy. The cutting process itself may then take many additional months by a master cutter working with the precision of a surgeon and the eye of an artist.
Why This Blue Diamond Discovery Matters Beyond the Gem
As remarkable as the diamond itself may be, its impact extends far beyond the global luxury market. On average, around 80 percent of the value generated by responsibly recovered diamonds remains within the local economies. That revenue will support jobs, infrastructure, education, healthcare, and essential social programs.
At the Cullinan Mine, responsible production is at the center of their operations. Petra Diamonds reports that 100 percent of procurement spend at its South African operations goes to local suppliers, further supporting the economy. Petra also prioritizes training, education, and skills development for people in the community, enabling long-term economic impact and job creation. Environmental stewardship also plays a critical role, with major efforts on energy efficiency, water use, and recycling, waste management, and biodiversity rehabilitation and protection.
This discovery carries profound meaning not only for collectors and connoisseurs but for the communities that benefit directly from its recovery.
What Comes Next for the 41.82-Carat Blue Diamond
For now, the 41.82-carat blue diamond discovery from Cullinan exists in a moment of anticipation. Its ultimate value, final size, and finished form remain unknown. Until then, the Cullinan Mine has once again proven why it remains one of the most legendary sources of natural diamonds in history.
