A 102-carat flawless diamond is going to be auctioned in the Hong Kong SAR in October, Sotheby's announced on Thursday. /CFP

In the size of an egg with D color flawless rating, the white sparkler is one of the rarest diamonds in the world. /CFP

It is also the second largest oval diamond of its kind that ever appeared in auctions, according to Sotheby's. The largest is a 118-carat diamond, which set a record price in 2013 of 30.8 million U.S. dollars. /CFP

The gem is going to be auctioned on October 5 in Hong Kong with an estimated hammer price of 12-30 million U.S. dollars (82-205 million Yuan). /CFP