Diamonds are really not that rare. Before the Second World War, the diamond industry was struggling with a crisis of oversupply and rapidly plummeting prices.

But with the formation of a diamond cartel, controlled by de Beers, diamond prices since then have been kept artificially high, even with new supply sources popping up such as Canada's in the 1990's. According to geology.com, Canada alone produced 11.2 million carats in 2003!!

However, coloured diamonds are indeed rare. These "fancies" can be a number of colours like green, blue, orange, brown and yellow. But the rarest of all is red. Just a few dozen specimens exist. The largest of them at 5.11 carats, is the Moussaieff Red which belongs to the Moussaieff Jewelers Ltd. It was found in the 1990's by a Brazilian farmer. The gemstone has been faceted using the triangular brilliant cut sometimes called the trillion or trilliant cut.

The Physics Factbook reported that red diamonds have sold for more than $3,900,000 per gram. For those of us whose bank accounts don't quite reach those heady heights, we can only drool at the picture of this gorgeous cranberry-coloured gem.

References
Wikipedia : Moussaieff Red Diamond
The Blue Mining Company : Diamond and Gold Production
Curious Notions : Rare Gemstones
Famous Diamonds : Moussaieff Red Diamond