The Moussaieff Red Diamond (formerly known as the Red Shield Diamond) is a diamond measuring 5.11 carats (1.022 g) with a triangular brilliant cut (sometimes called a trillion or a trilliant cut), rated in color as Fancy Red by the Gemological Institute of America. It is the world’s largest known red diamond, the rarest of them all.
The Moussaieff Red was discovered in the 1990s by a Brazilian farmer, in the Abaetezinho river in 1990, in a region known as Alto Paranaiba.
The rough stone weighed 13.9 carats (2.78 g). The diamond was purchased and cut by the William Goldberg Diamond Corp., where it went by its original name, the Red Shield.
It was purchased in 2001 or 2002 by Shlomo Moussaieff, an Israeli-born jewelry dealer in London, and is currently owned by Moussaieff Jewellers Ltd.
The Moussaieff Red was displayed in 2003 as part of the Smithsonian Institution’s “The Splendor of Diamonds” exhibit, alongside The De Beers Millennium Star and The Heart of Eternity.