--- title: "What Are the Most Common Myths About Pearls?" description: "Common pearl myths checked against the evidence: grains of sand, Cleopatra's pearl in vinegar, fake cultured pearls, dyed black pearls and the tooth test." canonical_url: "https://learnaboutpearls.com/basics/pearl-myths/" last_updated: "2026-11-04" last_reviewed: "2026-10-26" reviewed_by: "Simon" publisher: "Unique Pearl" publisher_disclosure: "Learn About Pearls is published by Unique Pearl, a pearl jeweler." --- # What Are the Most Common Myths About Pearls? **Short answer:** Several popular beliefs about pearls don't hold up. A grain of sand isn't what makes a pearl; museums describe pearls forming as a defense against an irritant such as a parasite, or after an injury. Cultured pearls are real pearls grown with human help, not fakes, and Tahitian pearls are dark by nature. Even Cleopatra's famous pearl in vinegar is chemically plausible, according to a 2010 study. **Key facts:** - Pearls form as a natural defense against an irritant such as a parasite entering the shell, or damage to the mollusk's body. [1] - When pearls are cultured, the irritant is inserted by hand. [1] - In the United States, a cultured pearl must be called cultured, and an imitation pearl is a manufactured product. [2] - CIBJO defines a Tahitian cultured pearl as naturally colored. [3] - Pliny the Elder told how Cleopatra dissolved a pearl in vinegar to win a wager with Antony. [4] - A 2010 study found that the acid strength of wine vinegar is ideal for dissolving a pearl. [5] - A gritty feel against the teeth suggests a real pearl, but the test can damage pearls and doesn't rule out every imitation. [6] 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](https://learnaboutpearls.com/glossary/#mollusk) 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](https://learnaboutpearls.com/glossary/#mantle) tissue that ends up in the wrong place and forms a [pearl sac](https://learnaboutpearls.com/glossary/#pearl-sac), which lays down [nacre](https://learnaboutpearls.com/glossary/#nacre). [8] The page [how pearls form](https://learnaboutpearls.com/basics/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](https://learnaboutpearls.com/glossary/#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](https://learnaboutpearls.com/glossary/#natural-pearl) does, but its growth requires human help. [11] A technician implants a piece of mantle tissue alone, or with a shell [bead](https://learnaboutpearls.com/glossary/#bead), into the host mollusk. [7] When pearls are cultured, the irritant is inserted by hand. [1] An [imitation pearl](https://learnaboutpearls.com/glossary/#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](https://learnaboutpearls.com/basics/natural-cultured-and-imitation-pearls/) sets out the differences. ## Myth: black pearls are always dyed [Tahitian cultured pearls](https://learnaboutpearls.com/glossary/#tahitian-cultured-pearl) 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. | Feature | Akoya cultured pearl | Freshwater cultured pearl | South Sea cultured pearl | Tahitian cultured pearl | | -------------- | --------------------------------- | ------------------------------------------------------------------- | ---------------------------------------------------------------- | -------------------------------------------------- | | Natural colors | white and cream [12, 13, 14, 15] | white, cream, pink, peach, orange, lavender and purple [3, 12, 15] | white, silver, cream, champagne and golden [11, 15, 16, 17, 18] | gray, greenish gray, black and brown [11, 13, 15] | Some dark pearls are [treated](https://learnaboutpearls.com/glossary/#treated-pearl), though. [Irradiation](https://learnaboutpearls.com/glossary/#irradiation) has darkened [freshwater cultured pearls](https://learnaboutpearls.com/glossary/#freshwater-cultured-pearl) since the 1960s, and some gray or blue [Akoya](https://learnaboutpearls.com/glossary/#akoya) are irradiated. [19] The page [dyed and treated pearls](https://learnaboutpearls.com/identification/dyed-and-treated-pearls/) explains how labs tell. ## Myth: the tooth test proves pearls are real The [tooth test](https://learnaboutpearls.com/glossary/#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](https://learnaboutpearls.com/glossary/#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](https://learnaboutpearls.com/identification/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](https://learnaboutpearls.com/glossary/#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](https://learnaboutpearls.com/wearing/pearls-for-weddings-and-graduations/) has more. ## Questions people ask ### Do pearls start from a grain of sand? A particle of sand can be the irritant, but it isn't what makes the pearl. The Natural History Museum in London describes pearls forming as a defense against an irritant such as a parasite, or damage to the animal's body, and the pearl itself grows from mantle tissue that forms a pearl sac. [1, 7, 8] ### Can a pearl dissolve in vinegar? Yes. Pearls are calcium carbonate, and acids attack them; in GIA's tests a dilute acid made a cultured pearl effervesce. A 2010 study of Cleopatra's legendary pearl cocktail found that the acid strength of wine vinegar is ideal for the reaction. [5, 6, 10] ### Are cultured pearls fake? No. A cultured pearl grows inside a living mollusk, as a natural pearl does, after a technician implants mantle tissue, with or without a shell bead. US rules define an imitation pearl as a manufactured product, and require cultured pearls to be called cultured. [2, 7] ### Are black pearls dyed? Tahitian cultured pearls aren't; CIBJO defines them as naturally colored. Some other dark pearls are treated, though. Irradiation has darkened freshwater cultured pearls since the 1960s, and some gray or blue Akoya are irradiated. [3, 19] ### Are real pearls always knotted? Knots are 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. Telling real pearls from imitations takes other tests. [20] ## References 1. Natural History Museum, London. How do oysters make pearls?. [Source](https://www.nhm.ac.uk/discover/quick-questions/how-do-oysters-make-pearls.html) · [Archived copy](https://web.archive.org/web/20261003100452/https://www.nhm.ac.uk/discover/quick-questions/how-do-oysters-make-pearls.html) 2. U.S. Federal Trade Commission (Electronic Code of Federal Regulations). 16 CFR Part 23, Guides for the Jewelry, Precious Metals, and Pewter Industries. [Source](https://www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-23) · [Archived copy](https://web.archive.org/web/20260907072405/https://www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-23) 3. CIBJO, The World Jewellery Confederation, Pearl Commission (2026). The CIBJO Pearl Book (Pearl Blue Book) 2026. [Source](https://cibjo.org/wp-content/uploads/2026/10/Pearl-Blue-Book-2026-.pdf) · [Archived copy](https://web.archive.org/web/20261025235254/https://cibjo.org/wp-content/uploads/2026/10/Pearl-Blue-Book-2026-.pdf) 4. Pliny the Elder; translated by John Bostock and H. T. Riley. 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[Source](https://www.gutenberg.org/cache/epub/6400/pg6400-images.html) · [Archived copy](https://web.archive.org/web/20261015091812/https://www.gutenberg.org/cache/epub/6400/pg6400-images.html) 10. Gemological Institute of America (GIA), Gem Encyclopedia. Pearl. [Source](https://www.gia.edu/pearl) · [Archived copy](https://web.archive.org/web/20260909031512/https://www.gia.edu/pearl) 11. Gemological Institute of America (GIA), Gem Encyclopedia. Pearl Description. [Source](https://www.gia.edu/pearl-description) · [Archived copy](https://web.archive.org/web/20261017085317/https://www.gia.edu/pearl-description) 12. Phoebe Shang (2026). Freshwater Akoyas – A Trending Misnomer for Certain Freshwater Pearls. [Source](https://www.gia.edu/freshwater-akoyas-a-trending-misnomer-for-certain-pearls) · [Archived copy](https://web.archive.org/web/20260617073835/https://www.gia.edu/freshwater-akoyas-a-trending-misnomer-for-certain-pearls) 13. Gemological Institute of America (GIA), FAQ. What are the main types of cultured pearls and what are their distinctive characteristics?. [Source](https://www.gia.edu/FAQ/gia-faq-about-gemstones-cultured-pearl-types-characteristics) · [Archived copy](https://web.archive.org/web/20260510233833/https://www.gia.edu/FAQ/gia-faq-about-gemstones-cultured-pearl-types-characteristics) 14. Artitaya Homkrajae (2024). Remarkably Large Akoya Bead Cultured Pearls. [Source](https://www.gia.edu/gems-gemology/summer-2024-gemnews-large-akoya-bead-cultured-pearls) · [Archived copy](https://web.archive.org/web/20261025235607/https://www.gia.edu/gems-gemology/summer-2024-gemnews-large-akoya-bead-cultured-pearls) 15. CIBJO Pearl Commission (2025). CIBJO Guides Describing and Classifying Natural and Cultured Pearls, the Producing Molluscs & Responsible Pearling. [Source](https://cibjo.org/wp-content/uploads/2025/12/Final-Guide-October-2025-v2-COMPRESSED.pdf) · [Archived copy](https://web.archive.org/web/20260212155210/https://cibjo.org/wp-content/uploads/2025/12/Final-Guide-October-2025-v2-COMPRESSED.pdf) 16. Smithsonian National Museum of Natural History. South Sea Pearl Ring (NMNH G10639). [Source](https://naturalhistory.si.edu/explore/collections/geogallery/10002784) · [Archived copy](https://web.archive.org/web/20250925205851/https://naturalhistory.si.edu/explore/collections/geogallery/10002784) 17. Shane Elen (2001). Spectral Reflectance and Fluorescence Characteristics of Natural-Color and Heat-Treated "Golden" South Sea Cultured Pearls. [Source](https://www.gia.edu/gems-gemology/summer-2001-heat-treated-golden-south-sea-cultured-pearls-elen) · DOI [10.5741/GEMS.37.2.114](https://doi.org/10.5741/GEMS.37.2.114) · [Archived copy](https://web.archive.org/web/20260308065638/https://www.gia.edu/gems-gemology/summer-2001-heat-treated-golden-south-sea-cultured-pearls-elen) 18. Chunhui Zhou, Artitaya Homkrajae, Joyce Wing Yan Ho, Akira Hyatt and Nicholas Sturman (2012). Update on the Identification of Dye Treatment in Yellow or "Golden" Cultured Pearls. [Source](https://www.gia.edu/gems-gemology/winter-2012-cultured-pearls-zhou) · DOI [10.5741/GEMS.48.4.284](https://doi.org/10.5741/GEMS.48.4.284) · [Archived copy](https://web.archive.org/web/20260309094817/https://www.gia.edu/gems-gemology/winter-2012-cultured-pearls-zhou) 19. Emiko Yazawa and Chunhui Zhou (2024). Irradiated and Dyed Akoya Pearls. [Source](https://www.gia.edu/gems-gemology/spring-2024-lab-notes-irradiated-and-dyed-akoya-pearls) · [Archived copy](https://web.archive.org/web/20240720120748/https://www.gia.edu/gems-gemology/spring-2024-lab-notes-irradiated-and-dyed-akoya-pearls) 20. Gemological Institute of America (GIA), Gem Encyclopedia. Pearl Buyer's Guide. [Source](https://www.gia.edu/pearl/buyers-guide) · [Archived copy](https://web.archive.org/web/20260613185853/https://www.gia.edu/pearl/buyers-guide) 21. Gemological Institute of America (GIA), Gem Encyclopedia. Pearl Quality Factors. [Source](https://www.gia.edu/pearl-quality-factor) · [Archived copy](https://web.archive.org/web/20261016075647/https://www.gia.edu/pearl-quality-factor) 22. Emily Post (1922). Etiquette in Society, in Business, in Politics and at Home. [Source](https://www.gutenberg.org/files/14314/14314-h/14314-h.htm) · [Archived copy](https://web.archive.org/web/20261012142430/https://www.gutenberg.org/files/14314/14314-h/14314-h.htm) **Written by:** Learn About Pearls editors **Fact-checked:** Learn About Pearls editors, October 26, 2026 **Reviewed by:** Simon, October 26, 2026 **First published:** November 4, 2026 **Publisher:** [Unique Pearl](https://learnaboutpearls.com/about/), a pearl jeweler **Revision history** 1. November 4, 2026: First published. First published **How to cite this page** **APA:** Learn About Pearls editors. (2026). _What Are the Most Common Myths About Pearls?_ Learn About Pearls. https://learnaboutpearls.com/basics/pearl-myths/ **MLA:** “What Are the Most Common Myths About Pearls?” _Learn About Pearls_, Unique Pearl, November 4, 2026, learnaboutpearls.com/basics/pearl-myths/. **Chicago:** Learn About Pearls editors. “What Are the Most Common Myths About Pearls?” Learn About Pearls. Unique Pearl. Last modified November 4, 2026. https://learnaboutpearls.com/basics/pearl-myths/. **BibTeX:** `@misc{lap-basics-pearl-myths, title = {What Are the Most Common Myths About Pearls?}, author = {{Learn About Pearls editors}}, year = {2026}, howpublished = {\url{https://learnaboutpearls.com/basics/pearl-myths/}}, note = {Learn About Pearls, published by Unique Pearl}}` Quoting with attribution and a link is welcome. See [how to cite and reuse](https://learnaboutpearls.com/cite/). **Suggest a correction** ## Related pages - [Basics](https://learnaboutpearls.com/basics/): What pearls are, what they are made of, and how natural, cultured and imitation pearls differ. - [How pearls form](https://learnaboutpearls.com/basics/how-pearls-form/): How natural and cultured pearls grow inside a mollusk, layer by layer. - [Is it a real pearl?](https://learnaboutpearls.com/identification/how-to-tell-if-pearls-are-real/): Simple checks that point to an imitation, what each one can and can't prove, and when to ask a lab.