The Gemological Institute of America (GIA) has examined the world’s second largest diamond, a rough stone weighing 2,488 carats, at its laboratory in Gaborone, Botswana.
Named “Motswedi”—meaning “water spring” in Setswana—the diamond was unearthed in August 2024 by Canadian miner Lucara at the Karowe mine, a site renowned for producing some of the world’s largest and rarest stones. At recovery the stone weighed 2,492 carats, but several tiny fragments detached during cleaning and handling account for the difference in size.
The GIA confirmed that “Motswedi” is a type IIa diamond: transparent, gem-quality, and unusually pure with no detectable nitrogen. Despite its immense size, the stone shows minimal inclusions and is divided internally into large, high-quality “blocks”. It is now recognised as the largest single-crystal diamond in existence, surpassed in weight only by the 3,106-carat “Cullinan Diamond”, recovered in South Africa in 1905.
“This is undoubtedly a diamond of great historical importance,” said Tom Moses, GIA’s executive vice president and chief laboratory officer. “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.”
Lucara has said “Motswedi” may remain unpolished as a museum piece, and discussions with several international institutions are under way. Whether cut for jewels or preserved in its rough state, the diamond is expected to become one of the most celebrated discoveries of the century. (Photo courtesy: GIA)
15-09-2025
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