Dubai: One of the largest saltwater pearls in the world insured for $5 million (Dh18.4 million) will be auctioned next month in Abu Dhabi and is expected to attract bids up to $8 million (about Dh29.5 million).

The pearl, which weighs 115 grams and is 575 carats, dates from the 12th century and originating from Mongolia according to Abdullah Abdul Qadir Al Muaini, head of the gemstone unit at the Dubai Central laboratory.

Money raised from the sale of the pearl, named Arco Valley pearl, will go towards children and humanitarian organizations as well as funding a Gulf Pearl traveling museum to revive interest in the virtually defunct regional pearl industry.

It is believed the pearl once belonged to Ghengis Khan's grandson, the Mongol emperor Kublai Khan, in the 13th century. The current owners of the Arco Valley Pearl, who have asked to remain anonymous, have had it in their possession for a number of decades.

The pearl measures 79 millimeters by 41 millimeters by 34 millimeters. It is the owner's wish that the pearl be renamed Abu Dhabi Pearl but the final decision will lie with whoever buys it, according to a statement read on behalf of the owners by auction manager Paul Fletcher of Lifestyle Auctions.

The auction will take place on May 3 at Emirates Palace in Abu Dhabi where bidders will attend the event, Pearl Night, by invitation.

Khaled Al Sayegh, a pearl trader, and the driving force behind the revival of the pearl industry, said the value of the Arco Valley pearl is based on its shape and colour.

It is classified as a natural blister pearl with a baroque shape, meaning it has an irregular shape. "Pearls in the Gulf have pink colours and a blueish twist when looked at in the light. I have never seen a pearl shaped like this before of this size, it is heart shape almost," said Al Sayegh, "This pearl is white with a twist of cream. It is the best pearl and people will be on their feet bidding for it," he added.

The pearl has been verified by the Dubai Central Laboratory. It has been partially drilled three times and then repaired to its original state.

Other pearls will be up for auction alongside the Arco Valley pearl.

The largest pearl in the world is called The Pearl of Allah and was found by a Muslim Filipino diver off the island of Palawan in 1934 and measures a record 24 centimetres long. It is stored in a museum.