Pearl Rotation Confirmed

Pearl Rotation Confirmed

Recently researchers from France, Qatar and French Polynesia have confirmed that oysters do turn pearls as part of the development process.

How did the researchers discover this?

The researchers used a specially created, modified magnetometer to watch the pearl inside the oyster. The magnetometer registered the magnetic field variations with magnetic sensors from movements of a magnetic nucleus inserted in the oyster.

pearl rotation british pearl association

How is a pearl cultured?

A cultured pearl is formed by inserting a nucleus and a small piece of mantle tissue into a living mollusc. In this case, the grafted pearl oyster was the Pinctada Margartifera oyster. The grafting process takes place after a piece of mantle tissue is inserted into the sexual organs (gonads) of the receiving oyster. Together with a shell based nucleus. After grafting has taken place they are then returned to the lagoons.

Once inserted into the receiving oyster , the cells of the graft multiply to form a pearl sac around the nucleus. The pearl sac then deposits calcium carbonate layers around the nucleus. And the pearl then takes approximately one year to cover the nucleus and form a sufficiently thick cover of nacre.

pearl rotation british pearl association

Ground Breaking Experiment

In this ground breaking experiment, 2 experimental grafts were implemented. Both in 2012 and the “receiving” oysters came from French Polynesia. After grafting they were placed in a net and hung up in a growing field in a lagoon in Tahiti.


The researchers were able to “view” the pearl being turned within the first 40 days after grafting the pearl. But the turning of the pearl was sporadic. However, after 40 days the nucleus rotation was continuous. During the growth of the pearls, the researchers were able to quantify that the pearl rotates continuously inside the oyster throughout its formation 12-18 months later.

pearl rotation british pearl association


The experiment confirms what scientists have always believed: that “yes” a pearl does turn during formation.


Royal Society Open Science

    “Yes it turns: An experimental evidence of pearl rotation during its formation.”

July 15th 2015