Fisherman, who has not been identified, found the priceless 34kg gem ten years ago in sea off the coast of Palawan Island, Philippines.
He didn't know the potential value and kept it as a good luck charm in his wooden home.
But a fire at the property earlier this year forced him to have a clear out and move house.The fisherman handed it in to the local tourism officer.
Tourism officer said: The fisherman threw the anchor down and it got stuck on a rock during a storm.He noticed that it was lodged on a shell and swam down to pull up the anchor.
The gem was shown off to the public today.
The current record holder is Pearl of Lao Tze, which was also found off Palawan, Philippines, in 1934.
The priceless rock measures a staggering 1ft foot wide and 2.2 feet long dwarfing the current world's biggest Pearl which weighed 6.4kg and is worth $35million.
Natural pearls are formed inside the shells of molluscs as a defence mechanism against a potentially threatening irritant, such as a parasite. Despite popular belief, pearls rarely grow from a grain of sand.
The animal creates a pearl sac and secretes calcium carbonate to seal off the irritation. This secretion process is repeated many times, producing a pearl.
The jewel increases in size as each new layer of calcium carbonate is deposited. Saltwater pearls usually take two to three years to develop, but larger pearls such as the one held in Puerto Princesca would have taken far longer.