File photo of De Beers Millennium Jewel 4 [File Photo: huffpostmaghreb.com]

A rare 10.1 carat blue diamond will be auctioned by Sotheby's Hong Kong next month.

The rare gem is called De Beers Millennium Jewel 4 and comes from a private collection in Asia. It is one of 12 blue diamonds in the De Beers Millennium collection.

Quek Chin Yeow, Deputy Chairman of Sotheby's Asia, is very impressed by the beautiful stone.

"And this stone was actually one of the most beautiful. It's a beautiful sky blue, compared to, say, the Blue Moon which is much more of the sea blue color. So, there are different shades of blue but the intensity is the thing that gives the vivid hue, and that is the difference between a lot of other stones. And, of course, for me to see the stone again, after, you know, a decade-and-a-half is really a great thrill and to be able to offer it back in Asia is really a tremendous honor."

The oval-shaped "Internally Flawless Fancy Vivid" blue diamond is estimated to be worth between 30 to 35 (m) million US dollars.

The collection is on display at an exhibition in Taipei this weekend and will be auctioned on April 5th in Hong Kong.