9. Moussaieff Red Diamond – est $20 million
The Moussaieff Red Diamond, once known as the Red Shield Diamond, is a small but rare 5.11 carat stone with a triangular brilliant cut. It’s colour was rated as Fancy Red by the Gemological Institute of America and it’s the largest red diamond currently known in the world. Discovered in the 1990s by a Brazilian farmer the stone originally weighed in at 13.9 carats. It was bought and cut by William Goldberg Diamond Corp, before being sold to Moussaieff Jewellers sometime in 2001 or 2002.