What Are the Most Common Myths About Pearls?

Pearls have gathered stories for as long as people have prized them. Some are old beliefs about where pearls come from; others are modern misunderstandings. Here is what the evidence says about the common ones.

Old ideas about where pearls come from#

People once had colorful explanations. GIA notes that ancient peoples of the Middle East believed pearls were teardrops fallen from heaven, the Chinese imagined that they came from the brain of a dragon, and Christopher Columbus and his contemporaries thought mollusks formed pearls from dew drops.⁷

Myth: every pearl starts with a grain of sand#

A particle of sand can be the irritant, GIA notes,⁷ but it isn’t what makes a pearl. The Natural History Museum in London describes pearls forming as a natural defense against an irritant such as a parasite entering the shell, or damage to the mollusk’s body.¹ The pearl itself grows from mantle tissue that ends up in the wrong place and forms a pearl sac, which lays down nacre.⁸ The page how pearls form explains the process.

Myth: Cleopatra’s pearl couldn’t have dissolved in vinegar#

The story comes from Pliny the Elder. To win a wager with Antony that she could spend ten million sesterces on a single meal, Cleopatra dropped one of her two great pearls into a vessel of vinegar, let it dissolve and swallowed it.⁴ The other pearl, Pliny adds, was later cut in two to hang from the ears of the statue of Venus in the Pantheon at Rome.⁴ Suetonius tells of the emperor Caligula drinking pearls of immense value dissolved in vinegar.⁹

Many modern scholars have dismissed the tale as fantasy. A 2010 study by the classicist Prudence Jones tested it and found that, for acetic acid and pearls, the concentration in vinegar made from wine is ideal.⁵

The chemistry is simple. Pearls are calcium carbonate,¹⁰ and in GIA’s tests a dilute acid made a cultured pearl effervesce.⁶ It is also why CIBJO, the international jewelry confederation, advises keeping pearls away from all acids.³

Myth: cultured pearls are fake#

A cultured pearl is a real pearl. It grows inside a living mollusk, as a natural pearl does, but its growth requires human help.¹¹ A technician implants a piece of mantle tissue alone, or with a shell bead, into the host mollusk.⁷ When pearls are cultured, the irritant is inserted by hand.¹

An imitation pearl is something else: a manufactured product. In the United States, cultured pearls must be described as cultured, and imitations as imitations.² The page natural, cultured and imitation pearls sets out the differences.

Myth: black pearls are always dyed#

Tahitian cultured pearls are dark by nature. CIBJO defines the Tahitian cultured pearl as naturally colored,³ and the table shows the natural colors of each main type in the Learn About Pearls dataset.

Some dark pearls are treated, though. Irradiation has darkened freshwater cultured pearls since the 1960s, and some gray or blue Akoya are irradiated.¹⁹ The page dyed and treated pearls explains how labs tell.

Myth: the tooth test proves pearls are real#

The tooth test has some truth in it. In GIA’s study of imitation pearls, cultured pearls felt gritty when rubbed gently against the edge of the front teeth, and the imitations felt smooth. But the authors warned that the test can damage pearls, and that a gritty feel doesn’t rule out every imitation.⁶ For valuable pearls, a laboratory gives the answer.

Myth: a knotted strand means real pearls#

Knotting is a way of stringing, not a test. GIA says experts recommend a knot between each pearl, so the pearls don’t rub against each other and a broken string doesn’t lose them all.²⁰ The page how to tell if pearls are real covers the tests that work.

Myth: pearls are white and round#

Pearls come in many colors; GIA lists white, black, gray, yellow, orange, pink, lavender, green and blue.¹⁰ They come in eight basic shapes, from round to baroque and circled.²⁰ Round is the hardest cultured pearl shape to grow, but well-formed pear, oval and baroque pearls are prized too.²¹

Myth: pearls mean tears#

The idea that pearls mean tears is a superstition. In 1922 the etiquette writer Emily Post noted that “pearls are supposed to mean tears,” and dismissed it, along with other gem lore, as unfounded superstition.²² Pearls have long been a traditional wedding gift.⁷ The page pearls for weddings has more.