Type IIa diamond of remarkable size with exceptional gemological qualities

CARLSBAD, Calif. – August 28, 2025 – In July 2025, staff from the Gemological Institute of America (GIA), including GIA Executive Vice President and Chief Research and Laboratory Officer Tom Moses and Vice President of Research and Development Dr. Wuyi Wang, examined a rough diamond weighing 2,488.32 carats—nearly 1.10 pounds (0.498 kilograms)—at the Institute’s laboratory in Gaborone, Botswana.

“This is undoubtedly a diamond of great historical importance,” said Tom Moses. “I have been fortunate to examine many significant, large and very rare diamonds, but I have never seen a gem quality diamond of nearly this size.”

Recovered in August 2024 by the Lucara Diamond Corporation at the Karowe diamond mine in Botswana, this diamond is second in size only to the legendary 3,106-carat Cullinan diamond, which was found in South Africa 120 years ago. Weighing 2,492 carats at recovery and generally known then as ‘the Lucara rough,’ the diamond was namedMotswedithrough a public competition in Botswana. ‘Motswedi’ meanswater springorsourcein Setswana, the national language of Botswana. Since beginning operations in 2012, the Karowe mine has gained international recognition for producing large, high-quality diamonds of remarkable rarity.

“Our examinations confirmed that the Motswedi is a single gem-quality crystal, type IIa diamond with no detectable nitrogen,” said Dr. Wuyi Wang. “It is the largest known single crystal diamond in existence and undoubtedly formed much deeper within the earth than the majority of diamonds.”

The GIA team examined the immense diamond, along with 1.50 carats of small fragments that had broken off during cleaning and examination by the mining company. That accounts for the difference in weight between the diamond at recovery and when GIA examined it. The examination revealed that the diamond is divided into several large gem-quality “blocks” with minimal inclusions.

Further details of the scientific examinations conducted by GIA are available in an article by Tom Moses and Wuyi Wang on GIA.edu:

GIA has the most comprehensive gemological research effort in the world. A global team of more than 60 scientists, researchers, and technical staff conducts in-depth research into the properties of diamonds, colored stones and pearls. This GIA-funded research underpins the Institute’s education programs and industry-leading laboratory services, supporting its mission to ensure public trust in gems and jewelry.

Tom Moses, GIA executive vice president and chief laboratory and research officer, examining the 2,488.32 carat Motswedi diamond at the GIA laboratory in Gaborone, Botswana, in July 2025. © GIA; photo by Wuyi Wang.

The 2,488.32 carat Motswedi diamond at the GIA laboratory in Gaborone, Botswana, in July 2025.© GIA, photo by Wuyi Wang.

For press inquiries, please contact Carlee Carter at ccarter@gia.edu.

About GIA

An independent nonprofit organization, GIA (Gemological Institute of America), established in 1931, is recognized as the world’s foremost authority in gemology. GIA invented the famous 4Cs of Color, Clarity, Cut and Carat Weight and, in 1953, created the International Diamond Grading System™ which is recognized around the world as the standard for diamond quality.

Through research, education, gemological laboratory services and instrument development, the Institute is dedicated to ensuring the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science and professionalism.

Visit GIA.edu.

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GIA Examines the World’s Second Largest Diamond

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