The world's largest natural pearl was found off the coast of the Philippines, on the island of Palawan.

An excerpt from the article 24 facts about Philippines

It was found in 2006 by a fisherman who didn't inform anyone about the find for ten years, finally carrying the pearl to a tourist office. It was quickly realized that the specimen was unique; it was 61 cm long, 30 cm wide, and weighed 34 kg. Gemmologists estimated the pearl's value at approximately $100 million.

It was formed under completely natural conditions, formed by the giant appendage (Tridacna gigas), the largest species of clam in the world.