Rare pink diamond could fetch $21 million at auction

STORY: This pink diamond could

fetch over $21 million at auction

The 11.15-carat gem

is seen as one of the world’s purest

(Kristian Spofforth, Sotheby's)

“They are exceptionally rare in nature. If you look at diamonds, we all know as diamonds as being beautiful, wonderful, natural beauties, of diamonds, only five percent of them are colored diamonds. Of colored diamonds, only three percent of those are pink."

“It's been named the William(son) Pink Star which is a wonderful tribute to, to other really famous diamonds that are very similar. So, the Williamson Pink is worn by the Queen in a beautiful Cartier brooch that she has. It was given to her in 1947 and came from the Williamson mine in Tanzania.

"The other link is to the CTF Pink Star which we sold, which is the only is the only other internally flawless, vivid pink, over 10 carats that has been sold at auction, so it's a wonderful tie-in there, and hence, the name Williamson Pink Star giving tribute to both of those diamonds.”

The "Williamson Pink Star" will go on

tour to Dubai, Singapore and Taipei

before going under the hammer

in Hong Kong on Oct. 5