The 41.82-carat blue diamond unearthered at the Cullinan mine in South Africa by Petra Diamonds.
Petra
A 41.28ct blue diamond has been unearthed at the famous Cullinan mine in South Africa, according to the mine operator, Petra Diamonds Limited. Experts believe that the Type 11b gem could be one of the most significant blue diamonds ever mined.
The stone, which is currently being analyzed, was described by the mining company as “a 41.82 carat Type IIb blue diamond of seemingly exceptional quality in terms of both its colour and clarity” in a release sent out January 13. Blue diamonds are amongst the rarest gemstones on earth, and owe their unusual and highly prized color to the presence of boron, which absorbs warmer tones.
Cullinan diamond mine showing the ‘big hole’ where the famous largest diamond was discovered, a rough gem-quality diamond at 3106.75 carats
getty
The Cullinan mine in South Africa, is famous for producing the Cullinan Diamond – the largest gem-quality diamond unearthed to date – which was broken down into nine separate stones eventually set into the British Crown Jewels, on display at the Tower of London. Over the past five years, it has produced between 1.4 and 1.9 million carats of diamonds annually.
The mine, which was discovered in 1902 and is expected to continue produce gemstones until the 2040s, is particularly well-known in the industry for rare blue diamonds of this kind, including the De Beers Cullinan Blue sold in 2022 for $57.5 million.
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Large stones like this are typically broken down into smaller diamonds after purchase, before being set into diamond jewelery. In 2025, Chopard unveiled the Insofu collection, a full suite of jewelry using stones cut from the same, rough emerald, which had been mined in 2022.
The hero piece from Chopard’s Insofu collection, featuring emeralds all cut from the same 6,225-carat rough stone.
Chopard
The huge emerald was first bought by a private buyer, before coming to the Swiss luxury jewelry house later, which employed specialist Indian cutters to work on the stone. From an astonishing 6,225 carats of rough emerald, they produced 850 carats of smaller emeralds, which, once cut and polished, became part of the extensive collection.
No-one knows whether the new blue diamond will follow a similar path, but experts believe it to be an important find. Only Natural Diamonds Watch & Jewelry editor and gemologist Grant Mobley call the stone “one of the rarest finds on earth” and predicts that them gem could be a record-breaker once its final value and size has been confirmed after analysis.