Ellendale Diamond Mine

The geological reasons why Ellendale is peerless when it comes to yellows are a bit hard to grasp, but they distil to this: even within the 0.1 per cent of diamonds that are yellow, not all yellows are created equal. More than 93 per cent of the 0.1 per cent are actually so pale that you could call them beige, or so dark as to be brown. You can knock out the pale primrose ones too, leaving only a rare few, in the colours of Van Gogh’s sunflowers, that radiate inner fire and make the top-notch category that is called 'fancy’. At Ellendale, about 20,700 carats of 'fancy yellows’ are mined each year. Yellow diamonds do turn up elsewhere, such as Lesotho and Botswana. The world’s most famous yellow, a 128.54-carat, brilliant-cut rock called the Tiffany Diamond – on permanent display at the jeweller’s New York flagship store – was found as a 287.42-carat rough in South Africa in 1877. But Ellendale represents today’s finest reliable source. It is for this reason that Tiffany & Co has forged a long-term alliance between its gem acquisition subsidiary, Laurelton Diamonds, and Kimberley Diamond Company, which owns the mine.

- Marion Hume

Great many thanks for sharing the info.

Useful links:
http://www.tiffany.com
http://www.gemdiamonds.com