The Pearl of Lao Tzu (also referred to as Pearl of Lao Tze and previously as Pearl of Allah) is the largest known pearl in the world. The pearl was found in the Palawan sea, which surrounds the island of Palawan in the Philippines, and was found by a Filipino diver. It is not considered a gemstone pearl, but is instead what is known as a "clam pearl" or "Tridacna pearl" from a giant clam. It measures 24 centimeters in diameter (9.45inches) and weighs 6.4 kilograms (14.1lb).
The pearl came from Brooke's Point, Palawan in the Philippines. Wilburn Cobb, an American who brought the pearl from the Philippines in 1939 and owned it until his death in 1979, published an account of how he came to own it in Natural History magazine. According to Cobb, he wanted to buy it from a Philippine tribal chief when he first heard of it in 1934, but the chief, a Muslim, did not want to sell because he considered the pearl sacred, in part because of its resemblance to the turbaned head of the Islamic prophet, Muhammad. However, Cobb relates, he saved the life of the chief's son, who was stricken with malaria, in 1936 and was given the pearl as a token of gratitude. Because of its sacred associations, the pearl came to be known as the Pearl of Allah.