‘Exceptional’ 41.82-Carat Blue Diamond Uncovered In South Africa

A 41.28ct, ice-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 among the rarest gemstones on earth, and owe their unusual and highly prized color to the presence of boron, which absorbs warmer tones.

One of two South African mines operated by Petra Diamonds, the Cullinan mine in South Africa is famous for producing the Cullinan Diamond—the largest gem-quality diamond unearthed to date, which yielded nine separate stones which were eventually set into the British Crown Jewels, on display at the Tower of London. Over the past five years, Petra reports that 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 to produce gemstones until the 2040s, is well-known in the industry for rare blue diamonds of this kind. It has previously produced the De Beers Cullinan Blue, sold in 2022 for $57.5 million, while a similarly sized 39ct rough blue diamond found at the mine in 2021 eventually sold for over $40 million. This is the first major blue diamond recovery at Cullinan since then.

According to Rapaport, the stone represents a “significant” find for the British-based mining company, which it reports as having suffered financially from the drop in demand for diamonds in recent years. A perfect storm of the rise in popularity of lab-grown diamonds, introduction of US tariffs, drop in weddings and squeeze in consumer spending has seen prices drop by up to 26% for one-carat natural diamonds, between 2022 and 2025.

Large stones like this are typically cut into smaller diamonds after purchase, before being set into diamond jewelry. In 2025 for example, Chopard unveiled the Insofu collection, a full suite of jewelry using stones cut from the same rough emerald, which had been mined in 2022 in Zambia.

The huge rough emerald was first bought by a private buyer, before coming to the Swiss luxury jewelry house. Chopard employed specialist Indian cutters to work on the stone, a process which took over a year and involved extensive study before they took up tools. 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, or be sold off as separate stones, 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 the gem could be a record-breaker once its final value and size has been confirmed.