How Large Can a Pearl Be?
Known giant pearls weigh far more than 6 kg, but the title depends on what is classified as a pearl and whether its provenance is authenticated. The Giga Pearl weighs 27.65 kg and is listed by Guinness World Records as the largest natural non-nacreous (blister) pearl. GIA certification has been reported for it.
The often-mentioned Pearl of Puerto from the Philippines is estimated at about 34 kg, but its origin and authenticity were widely reported as unconfirmed when it was discovered; it should not be called a certified world record without qualification. The Pearl of Lao Tzu, about 6.4 kg, was once considered the largest but has long been surpassed in mass. These are rare calcareous formations from giant clams, unlike familiar nacreous oyster pearls.