The Gemological Institute of America (GIA) has conducted an in-depth examination of the world’s second-largest known diamond — a spectacular 2,488.32-carat rough stone named Motswedi — at its advanced laboratory in Gaborone, Botswana.

Discovered in August 2024 by Lucara Diamond Corporation at the renowned Karowe mine, the diamond initially weighed 2,492 carats at the time of recovery. It now ranks just behind the legendary Cullinan diamond, a 3,106-carat gem unearthed in South Africa in 1905, in terms of size. The newly discovered stone was officially named Motswedi, which means “water spring” or “source” in Setswana, following a public naming competition in Botswana — a symbolic gesture honoring its national significance.

GIA’s scientific team has confirmed that Motswedi is a single, gem-quality, type IIA diamond crystal, making it the largest known diamond of this type. Type IIA diamonds are extremely rare and chemically pure, with no detectable nitrogen impurities. What sets Motswedi apart is not only its size but also its internal quality — the stone is divided into multiple large, gem-quality blocks with minimal inclusions, suggesting exceptional potential for high-value polished gems.

The slight reduction in weight — from 2,492 carats to 2,488.32 carats — is attributed to the loss of approximately 1.50 carats in micro-fragments during the cleaning and handling process by the mining company, a standard part of rough diamond recovery and preparation.

Since its opening in 2012, the Karowe mine has built a reputation for yielding some of the largest and most valuable diamonds in the world. The discovery of Motswedi further cements Karowe’s standing as a globally significant source of extraordinary stones, continuing Botswana’s legacy in the world of diamond mining.

The GIA’s comprehensive analysis of Motswedi has been documented in a detailed article authored by Tom Moses and Dr. Wuyi Wang, now available on the Institute’s official website. Their findings offer critical insights into the geological formation, structure, and gemological properties of this unprecedented diamond.

Founded in 1931, the Gemological Institute of America is the world’s leading authority in gemology. The nonprofit organization is best known for developing the 4Cs grading system (cut, color, clarity, and carat weight) and the International Diamond Grading System™, both of which continue to serve as the global standard for evaluating diamond quality. The GIA’s continued role in examining historic stones like Motswedi underscores its mission to ensure public trust through research, education, and unbiased gem evaluation.