A rough diamond weighing 2,488.32 carats – nearly 1.10 pounds (0.498 kilograms) – analysed recently by the Gemological Institute of America (GIA) is the world’s second largest to date.

The Type IIA diamond of remarkable size bears exceptional gemmological qualities, noted GIA.

GIA Executive Vice President and Chief Research and Laboratory Officer Tom Moses and Vice President of Research and Development Dr. Wuyi Wang examined the diamond at the institute’s laboratory in Gaborone, Botswana in July 2025.

“This is undoubtedly a diamond of great historical importance,” said 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 Lucara Diamond Corporation at its Karowe diamond mine in Botswana, this diamond is second in size only to the legendary 3,106-carat Cullinan Diamond found in South Africa 120 years ago. 

Weighing 2,492 carats at recovery and known then as “The Lucara Rough,” this latest diamond discovery was named "Motswedi" through a public competition in Botswana. “Motswedi” means water spring or source in 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 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.